                   FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

BARBARA PRETE; EUGENE PRETE,             
               Plaintiffs-Appellants,
                and
JASON DONNELL WILLIAMS,
                            Plaintiff,         No. 04-35285
                 v.
BILL BRADBURY, Secretary of State               D.C. No.
                                             CV-03-06357-ALA
of Oregon,                                      OPINION
               Defendant-Appellee,
OREGON AFL-CIO; TIMOTHY J.
NESBITT, Esq.,
            Defendant-Intervenors-
                           Appellees.
                                         
        Appeal from the United States District Court
                 for the District of Oregon
          Ann L. Aiken, District Judge, Presiding

                  Argued and Submitted
           September 12, 2005—Portland, Oregon

                   Filed February 22, 2006

     Before: Raymond C. Fisher, Ronald M. Gould, and
               Carlos T. Bea, Circuit Judges.

                    Opinion by Judge Bea




                              1859
                       PRETE v. BRADBURY                    1863


                          COUNSEL

Ross A. Day, Tigard, Oregon, for the appellant.

David E. Leith, Office of the Oregon Attorney General,
Salem, Oregon, for the appellees.

Margaret S. Olney, Portland, Oregon, for the intervenor-
appellees.


                          OPINION

BEA, Circuit Judge:

   We are called upon to decide whether Oregon Ballot Mea-
sure 26’s prohibition of payment to electoral petition signa-
ture gatherers on a piece-work or per signature basis
unconstitutionally burdens core political speech. Because the
district court did not clearly err in determining that the plain-
tiffs failed to establish that the challenged measure signifi-
cantly burdens speech, we cannot hold the Measure imposes
a severe burden under the First Amendment. Therefore,
because the defendant has established an important regulatory
interest in support of the Measure, the plaintiffs have failed to
prove that the prohibition violates the First Amendment.

                               I.

  In November 2002, Oregon voters approved Ballot Mea-
sure 26 (“Measure 26”), a voter initiative, by a margin of 75
percent to 25 percent. Measure 26 reads:
1864                      PRETE v. BRADBURY
     To protect the integrity of initiative and referendum
     petitions, the People of Oregon add the following
     provisions to the Constitution of the State of Oregon:
     It shall be unlawful to pay or receive money or other
     thing of value based on the number of signatures
     obtained on an initiative or referendum petition.
     Nothing herein prohibits payment for signature gath-
     ering which is not based, either directly or indirectly,
     on the number of signatures obtained.

Or. Const., art. IV, § 1b.1

   Barbara and Eugene Prete and Jason Williams (collectively
“plaintiffs”), as chief petitioners,2 later coordinated signature
gathering to place various initiative measures on the February
and November 2004 general election ballots. Oregon’s Elec-
tions Division office sent inquiry letters to plaintiffs in
November 2003, advising plaintiffs that the Elections Divi-
sion had received complaints alleging plaintiffs had paid sig-
 1
   Oregon’s Secretary of State issued an administrative rule interpreting
Measure 26. The rule states in part Measure 26:
    bans the practice of paying circulators or others involved in an
    initiative or referendum effort if the basis for payment is the
    number of signatures obtained. This means that payment cannot
    be made on a per signature basis. Employment relationships that
    do not base payment on the number of signatures collected are
    allowed. Allowable practices include: paying an hourly wage or
    salary, establishing either express or implied minimum signature
    requirements for circulators, terminating circulators who do not
    meet the productivity requirements, adjusting salaries prospec-
    tively relative to a circulator’s productivity, and paying discre-
    tionary bonuses based on reliability, longevity and productivity,
    provided no payments are made on a per signature basis.
Or. Admin. R. 165-014-0260. A violation of Measure 26 will result in
civil penalties of a minimum of $100 for each individual signature sheet
containing signatures collected in violation of Measure 26. Id.
   2
     Under Oregon law, a petition for a ballot measure must designate one
to three “chief petitioners,” who are the main sponsors of the measure. See
Or. Rev. St. § 250.045(3).
                            PRETE v. BRADBURY                            1865
nature gatherers on the basis of the number of signatures
collected, in violation of Measure 26. The inquiry letters
requested additional information from plaintiffs.3

   Plaintiffs responded by bringing an action in federal district
court against defendant, alleging Measure 26 violated the
First Amendment. Plaintiffs sought declaratory and injunctive
relief. Six days later, Tim Nesbitt and the Oregon AFL-CIO
(collectively “intervenor-defendants”) brought a motion to
intervene as of right under Fed. R. Civ. P. 24(a)(2), and alter-
natively, for permissive intervention under Fed. R. Civ. P.
24(b). Nesbitt, president of the Oregon AFL-CIO, was chief
petitioner for Measure 26, and the Oregon AFL-CIO was a
major supporter of Measure 26. Plaintiffs opposed the motion;
Bill Bradbury, in his official capacity as the Secretary of State
of Oregon (hereinafter “defendant”), did not. The district
court granted the motion to intervene as of right.

   Plaintiffs then brought a motion for a preliminary injunc-
tion to enjoin defendant from enforcing Measure 26. After
oral argument on the motion, the parties stipulated no further
discovery was needed and the court could issue a final ruling
on the merits pursuant to Fed. R. Civ. P. 65(a)(2).4
  3
     As the district court noted, the inquiry letters did not threaten prosecu-
tion, but “simply notif[ied] plaintiffs that complaints were filed and
request[ed] additional information. Nonetheless, the inquiry letters sent to
plaintiffs are sufficient to establish standing. For First Amendment pur-
poses, a plaintiff demonstrates an “injury-in-fact” where “the plaintiff
intends to engage in a course of conduct arguably affected with a constitu-
tional interest and that there is a credible threat that the challenged provi-
sion will be invoked against the plaintiff.” Arizona Right to Life PAC v.
Bayless, 320 F.3d 1002, 1006 (9th Cir. 2003) (internal quotation marks
omitted). Here, plaintiffs intended to engage in signature gathering where
payment is made per signature, and receipt of the inquiry letters is suffi-
cient to establish a “credible threat” that Measure 26 will be invoked
against plaintiffs.
   4
     The district court initially issued an opinion and order construing the
parties’ submissions as motions for summary judgment and granting sum-
1866                       PRETE v. BRADBURY
   In its amended opinion and order, the district court found
Measure 26 was targeted at electoral processes rather than at
the communicative aspect of petition circulation. The court
reasoned Measure 26 prohibited only one method of payment
for petition circulators, “a matter entirely between the circula-
tor, his or her employer, and the chief petitioner.” Next, the
court found Measure 26 imposed no severe or substantial bur-
dens on the circulation of initiative or referendum petitions,
and defendant’s interest in protecting the integrity of the ini-
tiative process justified the lesser burdens imposed by the
measure. The court, therefore, denied plaintiffs’ motion for a
preliminary injunction and entered judgment in favor of
defendant and intervenor-defendants. Plaintiffs timely
appealed.

   On appeal, plaintiffs assert (1) the district court erred in
granting intervenor-defendants’ motion to intervene as of
right, and (2) Measure 26 violates the First Amendment of the
United States Constitution. We have jurisdiction under 28
U.S.C. § 1291 and we hold: (1) the district court erred in
granting intervenor-defendants’ motion to intervene but that
error was harmless; and (2) the district court did not err in
determining plaintiffs failed to establish Measure 26 violates
the First Amendment.5 Accordingly, we AFFIRM the judg-
ment of the district court.

mary judgment for defendant and intervenor-defendants. The court later
vacated that opinion and order because the parties intended the court to
consolidate trial on the merits with plaintiffs’ motion for a preliminary
injunction, pursuant to Fed. R. Civ. P. 65(a)(2). The court then issued an
amended order and opinion, granting final judgment on the merits for
defendant and intervenor-defendants. Plaintiffs do not contest the steps
taken by the court to convert cross-motions for summary judgment to a
trial on the merits, and thus we consider the amended order and opinion
the final judgment of the trial court in this matter.
   5
     To be clear, we do not hold that Measure 26 is facially constitutional.
Rather, as discussed infra, we hold that because the district court did not
clearly err in determining plaintiffs failed to establish that Measure 26 sig-
                          PRETE v. BRADBURY                           1867
                                    II.

  This court reviews de novo a district court’s ruling on a
motion to intervene as of right pursuant to Fed. R. Civ. P.
24(a)(2). United States v. Alisal Water Corp., 370 F.3d 915,
918 (9th Cir. 2004).6

   [1] Under Fed. R. Civ. P. 24(a)(2),7 an applicant for inter-
vention as of right must demonstrate that: (1) the intervention
application is timely; (2) the applicant has a “significant pro-
tectable interest relating to the property or transaction that is
the subject of the action”; (3) “the disposition of the action

nificantly diminishes the pool of potential petition circulators, increases
the cost of signature gathering, or increases the invalidity rate of signa-
tures gathered, we cannot conclude that Measure 26 imposes a “severe
burden” under the First Amendment. Because plaintiffs have established
only a “lesser burden,” and defendant has offered “an important regulatory
interest” in preventing fraud, we conclude the district court did not err in
upholding the constitutionality of Measure 26 as applied. We express no
opinion, however, regarding whether Measure 26 could withstand strict
scrutiny had plaintiffs proven the measure imposed a “severe burden”
under the First Amendment. See Buckley v. Am. Constitutional Law
Found., 525 U.S. 182, 192 (1999) (requiring plaintiffs to establish the
challenged restrictions resulted in a significant decrease in the available
pool of petition circulators to support a finding of a “severe burden”).
   6
     This court reviews for abuse of discretion a district court’s ruling on
a motion for permissive intervention pursuant to Fed. R. Civ. P. 24(b)(2).
Kootenai Tribe of Idaho v. Veneman, 313 F.3d 1094, 1110 (9th Cir. 2002).
Although intervenor-defendants brought a motion in the alternative for
permissive intervention, the district court did not rule on that motion
because it granted the motion to intervene as of right.
   7
     Fed. R. Civ. P. 24(a)(2) provides in part:
    Upon timely application anyone shall be permitted to intervene
    in an action . . . when the applicant claims an interest relating to
    the property or transaction which is the subject of the action and
    the applicant is so situated that the disposition of the action may
    as a practical matter impair or impede the applicant’s ability to
    protect that interest, unless the applicant’s interest is adequately
    represented by existing parties.
1868                   PRETE v. BRADBURY
may, as a practical matter, impair or impede the applicant’s
ability to protect its interest”; and (4) “the existing parties
may not adequately represent the applicant’s interest.” Alisal
Water Corp., 370 F.3d at 919 (internal quotation marks and
citations omitted). Although the party seeking to intervene
bears the burden of showing those four elements are met, “the
requirements for intervention are broadly interpreted in favor
of intervention.” Id.

    A.   Timeliness, “Significant Protectable Interest,”
                      and Impairment

   [2] Here, plaintiffs wisely concede the intervenor-
defendants’ application was timely and the intervenor-
defendants have a “significant protectable interest” relating to
the subject of this action. First, intervenor-defendants brought
the motion to intervene only six days after plaintiffs brought
the action. Second, for purposes of intervention as of right, a
public interest group that has supported a measure (such as an
initiative) has a “significant protectable interest” in defending
the legality of the measure. Sagebrush Rebellion, Inc. v. Watt,
713 F.2d 525, 528 (9th Cir. 1983). Third, an adverse court
decision on such a measure may, as a practical matter, impair
the interest held by the public interest group. Id.

   [3] In Sagebrush Rebellion, this court held that a public
interest group may have a protectable interest in defending the
legality of a measure it had supported. Id. at 527. There, a
public interest group which had supported the creation of a
conservation area in Idaho sought to intervene on behalf of
the government in an action challenging the federal statute
that created that conservation area. Id. at 526. The district
court denied the motion to intervene. This court reversed,
holding the group had a protectable interest in defending the
creation of the conservation area. We stated in broad language
that “a public interest group [is] entitled as a matter of right
to intervene in an action challenging the legality of a measure
which it had supported.” Id. at 527. Further, an adverse deci-
                       PRETE v. BRADBURY                      1869
sion against the conservation area “would impair the society’s
interest in the preservation of birds and their habitats,” an
interest the conservation area was designed to protect. Id. at
528. This court also held the government’s representation of
the group’s interest “may be inadequate” (for reasons dis-
cussed infra); thus, this court reversed and remanded to the
district court for it to grant the motion to intervene. Id. at 529.

   [4] Here, Nesbitt was chief petitioner for the measure, and
the Oregon AFL-CIO was a main supporter of the measure.
Under the rule from Sagebrush Rebellion, intervenor-
defendants thus have a “significant protectable interest”
related to this action, and an adverse judgment might impede
or impair that interest.

   Plaintiffs contend, however, that Arizonans for Official
English v. Arizona, 520 U.S. 43 (1997) (hereinafter “AOE”),
controls here and bars initiative sponsors from intervening in
judicial challenges to the initiative. Plaintiffs misread AOE.
There, the plaintiff (Yniguez), a state employee, brought an
action against the State of Arizona alleging the adoption of an
initiative which declared English “the official language of
[Arizona]” violated the First Amendment. Id. at 49. Yniguez
complained she often spoke Spanish with Spanish-speaking
persons as part of her state job, and the initiative’s mandate
for state employees to “act in English” could expose her to
sanctions. Id. at 50. After a bench trial, the district ruled the
initiative was unconstitutional as overbroad. Id. at 54. The
Arizonans for Official English Committee (“AOE”)—which
was the principal sponsor of the initiative—then brought a
motion to intervene, seeking to defend the constitutionality of
the initiative on appeal. Id. at 56. The district court denied the
motion. Yniguez then resigned from her employment with the
state. AOE appealed nonetheless, and this court determined
AOE had Article III standing to pursue the appeal in defense
of the initiative, and the action was not moot because of
Yniguez’s resignation. Id. at 58-60. The U.S. Supreme Court
reversed. The Court observed that AOE was not an elected
1870                      PRETE v. BRADBURY
representative, nor did any Arizona state law appoint initiative
sponsors as agents “to defend, in lieu of public officials, the
constitutionality of initiatives made law of the State.” Id. at
65. On that basis, the Court stated: “We thus have grave
doubts whether AOE . . . ha[s] standing under Article III to
pursue appellate review. Nevertheless, we need not defini-
tively resolve the issue. Rather, we will follow a path we have
taken before and inquire, as a primary matter, whether origi-
nating plaintiff Yniguez still has a case to pursue.” Id. at 66.
The Court concluded Yniguez’s resignation after the district
court’s judgment but before appeal mooted the case, and the
Court then vacated the decision of the district court and the
court of appeals. Id. at 72, 75.

   [5] AOE did not hold that initiative sponsors do not have
an interest in defending the initiative sufficient to support
intervention. The main issue presented in AOE was whether
the intervenor-applicant there had Article III standing to pur-
sue an appeal when a step taken by the original plaintiff (res-
ignation of her job) rendered the entire case or controversy
moot. Such a scenario is not at issue here.8 Therefore, we hold
  8
    There is some question, however, whether an intervenor-applicant must
independently establish Article III standing to intervene as of right. For
example, in the case at hand, Article III standing is satisfied between
plaintiffs and defendant. But a circuit split exists whether an intervenor-
applicant must also independently satisfy Article III standing to intervene
as of right. Compare Planned Parenthood of Mid-Missouri & Eastern
Kansas, Inc. v. Ehlmann, 137 F.3d 573, 576-77 (8th Cir. 1998) (requiring
independent intervenor standing) and Building & Const. Trades Dep’t v.
Reich, 40 F.3d 1275, 1282 (D.C. Cir. 1994) (same), with Associated Build-
ers & Contractors v. Perry, 16 F.3d 688, 690 (6th Cir. 1994) (no indepen-
dent intervenor standing required), and U.S. Postal Serv. v. Brennan, 579
F.2d 188, 190 (2d Cir. 1978) (same). The U.S. Supreme Court has not yet
settled the issue. See 7C Charles Alan Wright et al., Federal Practice and
Procedure § 1908 (2d ed. 2005). This court also has not definitively ruled
on the issue. Although some sources (such as Federal Practice and Proce-
dure) cite Yniguez v. Arizona, 939 F.2d 727 (9th Cir. 1991), for the propo-
sition that this court does not require independent Article III standing for
intervenors, id. at 731, that opinion was vacated by the U.S. Supreme
                          PRETE v. BRADBURY                          1871
that under Sagebrush Rebellion, intervenor-defendants have a
“significant protectable interest” related to this action and an
adverse judgment may impair or impede that interest.

                B.   Adequacy of Representation

   A closer issue is presented whether intervenor-defendants
established that “the existing parties may not adequately rep-
resent the applicant’s interest.” See Alisal Water Corp., 370
F.3d at 919. Plaintiffs contend that because defendant is
defending the constitutionality of Measure 26, intervenor-
defendants’ interest in defending the constitutionality of Mea-
sure 26 is adequately represented. The district court disagreed,
concluding defendant might not adequately represent
intervenor-defendants’      interests   because      intervenor-
defendants “claim an interest in preventing the gathering and
eventual counting of invalid signatures for initiatives oppos-
ing union interests,” and thus defendant possibly could make
different arguments than intervenor-defendants.

   [6] In assessing whether a present party will adequately
represent an intervenor-applicant’s interests, we “consider
several factors, including whether [a present party] will
undoubtedly make all of the intervenor’s arguments, whether
[a present party] is capable of and willing to make such argu-
ments, and whether the intervenor offers a necessary element
to the proceedings that would be neglected.” Sagebrush
Rebellion, 713 F.2d at 528. The burden of showing inade-
quacy of representation is minimal and “is satisfied if the

Court. See AOE, 520 U.S. at 80; League of United Latin Am. Citizens v.
Wilson, 131 F.3d 1297, 1305 n.5 (9th Cir. 1997) (noting Yniguez was
vacated by the U.S. Supreme Court and “is thus wholly without preceden-
tial authority”). Regardless, we need not reach this issue because, as dis-
cussed infra, the district court erred in granting intervenor-defendants’
motion to intervene on grounds other than whether intervenor-defendants
had independent standing.
1872                   PRETE v. BRADBURY
applicant shows that representation of its interests ‘may be’
inadequate . . . .” Id. (internal citations omitted).

   [7] Although the burden of establishing inadequacy of rep-
resentation may be minimal, the requirement is not without
teeth:

    The most important factor in determining the ade-
    quacy of representation is how the interest compares
    with the interests of existing parties. When an appli-
    cant for intervention and an existing party have the
    same ultimate objective, a presumption of adequacy
    of representation arises. If the applicant’s interest is
    identical to that of one of the present parties, a com-
    pelling showing should be required to demonstrate
    inadequate representation.

Arakaki v. Cayetano, 324 F.3d 1078, 1086 (9th Cir. 2003)
(internal citations omitted). Additionally, “[t]here is also an
assumption of adequacy when the government is acting on
behalf of a constituency that it represents. In the absence of
a very compelling showing to the contrary, it will be pre-
sumed that a state adequately represents its citizens when the
applicant shares the same interest.” Id. (internal citations and
quotation marks omitted).

   In Sagebrush Rebellion, discussed supra, we held the pub-
lic interest group seeking to intervene as of right established
that the defendant (the Secretary of the Interior) might not
adequately represent the group’s interest. 713 F.2d at 528. We
reasoned that the Secretary of the Interior, James Watt, had
previously been head of the foundation which was represent-
ing the plaintiff in the present action. Thus, the public interest
group—intervening on the defendant’s side—might bring a
perspective materially different from that of the present par-
ties and was entitled to intervene. Id.
                           PRETE v. BRADBURY                           1873
   In League of United Latin Am. Citizens v. Wilson, however,
this court recognized that when an intended intervenor and a
party in the action seek the same ultimate objective, a pre-
sumption arises that the intervenor’s interests are adequately
presented. 131 F.3d 1297. In League of United Latin Am. Citi-
zens, the plaintiff brought a lawsuit challenging California’s
Proposition 187, which had been enacted into law. Id. at 1300.
A public interest group brought a motion to intervene as of
right, claiming it participated in the drafting and sponsorship
of the proposition and desired to intervene in support of its
defense. Id. at 1301. The district court denied the motion, and
we affirmed. This court recognized the defendant (the State of
California) and the public interest group sought the same ulti-
mate objective—i.e., to defend the constitutionality of Propo-
sition 187—and thus a presumption of adequacy of
representation arose. Id. at 1305. Hence, we held the
intervenor-applicant’s interests were adequately represented
by the state defendant and affirmed the denial of the motion
to intervene.9

   [8] Here, the ultimate objective for both defendant and
intervenor-defendants is upholding the validity of Measure
26. Thus, a presumption arises that defendant is adequately
representing intervenor-defendants’ interests. See id. at 1305.
Second, defendant is the Oregon government, and intervenor-
defendants (the Oregon AFL-CIO and its president) share the
same interest with defendant, i.e., defending Measure 26.
Therefore, it is assumed that defendant is adequately repre-
senting intervenor-defendants’ interests. Arakaki, 324 F.3d at
1086. While it is unclear whether this “assumption” rises to
the level of a second presumption, or rather is a circumstance
  9
   Further, the court distinguished Sagebrush Rebellion, noting that in
that case the defendant, Secretary of the Interior Watt, had previously
served as the head of the foundation representing the plaintiff. Id. at 1305.
In League of United Latin Am. Citizens, however, this court noted that the
defendant had vigorously defended Proposition 187, and there was no evi-
dence the defendant would cease to do so in the future. Id.
1874                       PRETE v. BRADBURY
that strengthens the first presumption, it is clear that “[i]n the
absence of a ‘very compelling showing to the contrary,’ it will
be presumed that” the Oregon government adequately repre-
sents the interests of the intervenor-defendants. See id.

   Intervenor-defendants fail to present that compelling show-
ing of inadequate representation. In their motion to intervene,
intervenor-defendants stated first that defendant may not be
able to provide a complete defense of Measure 26 due to
“budget constraints.” Virtually all governments face budget
constraints generally, and if such a basis were sufficient to
establish inadequate representation, it would eliminate the
presumption of adequate representation when the government
and the intervenor-applicant share the same interest. Most
importantly, there is no evidence in the record that defendant
is unable to mount an effective defense of Measure 26 due to
alleged “budget constraints.” See League of United Latin Am.
Citizens, 131 F.3d at 1307 (citing Moosehead San Dist. v.
S.G. Phillips Corp., 610 F.2d 49, 54 (1st Cir. 1979) (holding
“a petitioner must produce something more than speculation
to the purported inadequacy in order to justify intervention as
of right”)).10

   Second, intervenor-defendants assert defendant “may be
inclined [to] give an unnecessarily narrow construction of
Measure 26 in the face of legal attacks on the measure.” Yet
neither plaintiffs nor defendant have argued for a narrowing
construction of Measure 26, and Measure 26 does not seem
susceptible to any narrowing construction.11 Thus, intervenor-
   10
      We do not hold that budgetary constraints that impact the ability of the
government to adequately litigate its position can never support a motion
to intervene as of right by a citizen of that government. Rather, we hold
only that absent any evidence of Oregon’s alleged budgetary constraints
and the impact of said constraints on this litigation, intervenor-defendants
failed to meet their burden to present a compelling showing of inadequate
representation.
   11
      Intervenor-defendants also argue that Measure 26 protects their inter-
est in “preventing fraudulent signatures from being gathered for initiatives
                            PRETE v. BRADBURY                            1875
defendants have failed to present evidence sufficient to meet
their burden of a “compelling showing” on this score as well.

   Third, intervenor-defendants contend defendant “does not
have the breadth of knowledge regarding the signature gather-
ing process to fully develop the record and respond to plain-
tiff’s factual allegations.” Intervenor-defendants assert they
have “particular expertise in the subject of the dispute.” For
example, they “have direct knowledge and experience in how
well a signature gathering campaign staffed by hourly circula-
tors can run.”

   Yet defendant, as Oregon’s Secretary of State, is undoubt-
edly familiar with the initiative process and the requisite
signature-gathering; indeed, defendant is the government
party responsible for counting the signatures.12 Defendant also
administers Oregon’s election processes and promulgates reg-
ulations to give effect to the state’s election statutes. See Or.
Admin. R. 165-014-0260 (interpreting Measure 26). Although
intervenor-defendants may have some specialized knowledge
into the signature gathering process, they provided no evi-
dence to support their speculation that the Secretary of State
lacks comparable expertise. To the contrary, defendant pre-
sumably is sufficiently acquainted with the signature gather-
ing process and could also acquire additional specialized

that are contrary to their union interests,” and defendant may not defend
that interest. We will read this claim as evincing an interest in preventing
fraudulent signatures on all petitions, not just those petitions which are
“contrary to their union interests.” We are left ignorant of what constitutes
intervenors’ union interests, if any, apart from preventing fraudulent sig-
natures on petitions. Absent any basis for determining there are “union
interests” separate and distinct from the prevention of fraudulent signa-
tures, we see no basis for intervention on this score.
   12
      To be precise, the Oregon Secretary of State does not count every sig-
nature on the petitions. Instead, it employs a statistical sampling technique
to determine whether the petitions contain the requisite number of signa-
tures to support certification of the initiative for the ballot. Or. Rev. Stat.
§ 250.105(4).
1876                       PRETE v. BRADBURY
knowledge through discovery (e.g., by calling upon
intervenor-defendants to supply evidence) or through the use
of experts.13 Thus, such a reason is insufficient to provide the
“compelling showing” necessary to overcome the presump-
tion of adequate representation discussed supra.

   [9] Accordingly, while we emphasize that the burden of
showing inadequacy of representation is generally minimal,
here intervenor-defendants failed to present evidence suffi-
cient to support a finding that their interests are not ade-
quately represented by the defendant in this action. We hold,
therefore, that the district court erred in granting the motion
to intervene as of right.

                              C.    Remedy

  The remedy for an improper grant of intervention has not
been clearly established. It is more common for appellate
courts to consider the denial of a motion to intervene,14 and
   13
      While we recognize intervenor-defendants may have greater first-hand
knowledge than the Secretary of State regarding the impact of Measure 26
on petition circulation, it will often be the case that a private party has
greater first hand knowledge of the impact of legislation on private indi-
viduals than the government. Such knowledge may support a trial judge’s
discretionary grant of permissive intervention, but it is not sufficient by
itself to support intervention as of right in this case. See Garza v. County
of Los Angeles, 918 F.2d 763, 777 (9th Cir. 1990) (Unlike intervention as
of right, “[t]he decision to grant or deny [permissive] intervention is dis-
cretionary, subject to considerations of equity and judicial economy.”
Therefore, while an interest may not be “sufficiently weighty to warrant
intervention as of right, the court may nevertheless consider eligibility for
permissive intervention under Fed.R.Civ.Pro. 24(b)(2).”). In this case
intervenor-defendants failed to present any evidence that the Oregon gov-
ernment could not have obtained any knowledge it lacked through the use
of discovery and expert testimony. Absent such evidence, intervenor-
defendants failed to make a compelling showing of inadequate representa-
tion sufficient to support intervention as of right.
   14
      The reason for this disparity is straightforward: the denial of a motion
to intervene is a final order and is thus immediately appealable. See
Stringfellow v. Concerned Neighbors in Action, 480 U.S. 370, 375-76
(1987). Yet the grant of a motion to intervene is not a final order and is
not appealable until after final judgment. Id. at 379-80.
                           PRETE v. BRADBURY                           1877
the few cases reversing the grant of a motion to intervene are
distinguishable because here the district court did not enter
separate judgments for the defendant and the intervenor-
defendants as in the cited cases, but entered a single judgment
in favor of both defendant and intervenor-defendants: that
Measure 26 does not violate the First Amendment.15

   Here, the district court erred in granting intervention as of
right and thereby allowing intervenor-defendants to present
evidence and argument. Under 28 U.S.C. § 211116 and Federal
Rule of Civil Procedure 61,17 however, we may not reverse
  15
      See Mothersill D.I.S.C. Corp. v. Petroleos Mexicanos, S.A., 831 F.2d
59, 60-63 (5th Cir. 1987) (the plaintiff brought a contracts action against
the defendant, and the parties agreed to settle; a corporate employee
moved to intervene as of right, claiming he was due payment for services
rendered under the contracts; the district court granted the motion to inter-
vene and later entered judgment for the intervenor, awarding him payment
for past services under the contracts; the Fifth Circuit reversed, holding
intervention was improper and vacating the judgment in favor of the inter-
venor.); Stockton v. United States, 493 F.2d 1021, 1022-24 (9th Cir. 1974)
(the plaintiff sought a tax refund from the defendant, and the district court
entered judgment for the plaintiff; the plaintiff’s attorney then moved to
intervene as of right, claiming an interest in his attorneys fees (to be paid
from the refund recovery); the district court granted the motion to inter-
vene and granted judgment for the plaintiff’s attorney; this court reversed,
holding intervention was improper and vacating judgment for the interve-
nor).
   16
      “On the hearing of any appeal or writ of certiorari in any case, the
court shall give judgment after an examination of the record without
regard to errors or defects which do not affect the substantial rights of the
parties.” 28 U.S.C. § 2111.
   17
      No error in either the admission or exclusion of evidence and no
      error or defect in any ruling or order or in anything done or omit-
      ted by the court or by any of the parties is ground for granting a
      new trial or for setting aside a verdict or for vacating, modifying,
      or otherwise disturbing a judgment or order, unless refusal to take
      such action appears to the court inconsistent with substantial jus-
      tice. The court at every stage of the proceeding must disregard
      any error or defect in the proceeding which does not affect the
      substantial rights of the parties.
Fed. R. Civ. P. 61.
1878                       PRETE v. BRADBURY
the district court’s judgment unless this error affected the
“substantial rights of the parties.” Cf. Texas Co. v. Hogarth
Shipping Corp., 256 U.S. 619, 629 (1921) (applying harmless
error review to the erroneous grant of intervention as amicus
curiae); Alaska v. Suburban Propane Gas Corp., 123 F.3d
1317, 1321-22 (9th Cir. 1997) (applying harmless error
review under Rule 61 to the erroneous denial of a motion to
intervene); California ex rel. State Lands Com’n v. United
States, 805 F.2d 857, 866 n.6 (9th Cir. 1986) (declining to
“consider whether or under what circumstances an erroneous
grant of intervention could constitute reversible error under
Fed. R. Civ. P. 61”); Hackin v. Lockwood, 361 F.2d 499 (9th
Cir. 1966) (the improper joinder of a civil defendant does not
prevent this court from addressing the merits of the action as
to the proper parties).

   [10] Here, the district court’s error in granting the motion
to intervene did not affect the substantial rights of the parties.
In its amended opinion and order, the district court discussed
only one piece of evidence submitted by intervenor-
defendant: an affidavit submitted by Ted Blaszak of Democ-
racy Resources of Oregon, Inc., a signature-gathering firm.
Blaszak averred that the requirement to pay petition circula-
tors by the hour rather than by the signature did not signifi-
cantly increase his costs or decrease productivity. Although
helpful to defendant’s case, the evidence was not crucial. As
noted infra in footnote 21, consideration of that affidavit does
not make it more probable than not that the district court’s
error tainted the judgment.18
  18
    In addition, had the district court denied Nesbit and the Oregon AFL-
CIO’s motion to intervene, defendant could have offered the same evi-
dence in cooperation with Nesbitt and the Oregon AFL-CIO. Moreover,
Nesbitt and the Oregon AFL-CIO could have presented argument as
amicus rather than as a full-fledged party. There is nothing in the record
to suggest that the status of Nesbitt and the Oregon AFL-CIO as interve-
nors, rather than as amici, materially affected plaintiffs’ pre-trial prepara-
tion, discovery, trial tactics (such as its motion for summary judgment) or
the case as a whole. For instance, nothing indicates that intervenor-
defendants paid defendant’s litigation expenses conditioned on intervenors
procuring intervenor status.
                          PRETE v. BRADBURY                           1879
   [11] Accordingly, the district court erred in granting
intervenor-defendants’ motion to intervene as of right, but the
error was harmless and, therefore, does not require vacating
the judgment of the district court.

                                   III.

   In reviewing a district court’s final judgment after consoli-
dation of its preliminary injunction ruling with its decision on
the merits pursuant to Fed. R. Civ. P. 65(a)(2),19 we review
the district court’s factual findings for clear error and its con-
clusions of law de novo. Associated Builders & Contractors
of S. California v. Nunn, 356 F.3d 979, 984 (9th Cir. 2004).
When the issue presented involves the First Amendment,
however, the standard of review is modified slightly. Histori-
cal questions of fact (such as credibility determinations or
ordinary weighing of conflicting evidence) are reviewed for
clear error, while constitutional questions of fact (such as
whether certain restrictions create a “severe burden” on an
individual’s First Amendment rights) are reviewed de novo.
Planned Parenthood of the Columbia/Willamette, Inc. v. Am.
Coalition of Life Activists, 290 F.3d 1058, 1070 (9th Cir.
2002).

   [12] The First Amendment, incorporated and made applica-
ble to the states by the Fourteenth Amendment, prohibits state
governments from enacting a “law . . . abridging the freedom
of speech.” McIntyre v. Ohio Elections Comm’n, 514 U.S.
334, 336 & n.1 (1995). As discussed infra, the circulation of
initiative and referendum petitions involves “core political
speech,” and is, therefore, protected by the First Amendment.
See Meyer v. Grant, 486 U.S. 414, 421-22 (1988).
  19
    Fed. R. Civ. P. 65(a)(2) provides in part: “Before or after the com-
mencement of the hearing of an application for a preliminary injunction,
the court may order the trial of the action on the merits to be advanced and
consolidated with the hearing of the application.”
1880                   PRETE v. BRADBURY
   [13] The First Amendment does not, however, prohibit all
restrictions upon election processes: “States may, and inevita-
bly must, enact reasonable regulations of parties, elections,
and ballots to reduce election- and campaign-related disor-
der.” Timmons v. Twin Cities Area New Party, 520 U.S. 351,
358 (1997). Indeed, the U.S. Supreme Court has recognized
“States allowing ballot initiatives have considerable leeway to
protect the integrity and reliability of the initiative process, as
they have with respect to election processes generally.” Buck-
ley, 525 U.S. at 191 (1999).

  For purposes of determining whether a state election law
violates an individual’s First Amendment rights, we

    weigh the character and magnitude of the burden the
    State’s rule imposes on those rights against the inter-
    ests the State contends justify that burden, and con-
    sider the extent to which the State’s concerns make
    the burden necessary. Regulations imposing severe
    burdens on plaintiffs’ rights must be narrowly tai-
    lored and advance a compelling state interest. Lesser
    burdens, however, trigger less exacting review, and
    a State’s important regulatory interests will usually
    be enough to justify reasonable, nondiscriminatory
    restrictions.

Arizona Right to Life Political Action Comm., 320 F.3d at
1007-08 (quoting Timmons, 520 U.S. at 358) (emphases
added and internal quotation marks omitted). The U.S.
Supreme Court has counseled against establishing any bright-
line rule in this field: “no litmus-paper test will separate valid
ballot-access provisions from invalid interactive speech
restrictions; we have come upon no substitute for the hard
judgments that must be made.” Buckley, 525 U.S. at 192
(internal quotation marks omitted).

  In Meyer v. Grant, the Supreme Court recognized the
expressive nature of petition circulation and held the whole-
                       PRETE v. BRADBURY                      1881
sale prohibition of paid petition circulators imposed an imper-
missible burden on free speech under the First Amendment.
486 U.S. 414. In Meyer, the plaintiffs challenged an amend-
ment to the Colorado constitution which made it a felony to
pay money or anything of value to petition circulators who
circulated initiative or referendum petitions. Id. at 415. After
a bench trial, the district court upheld the statute, but the court
of appeals reversed. Id. at 418-420. The U.S. Supreme Court
affirmed, explaining:

    The circulation of an initiative petition of necessity
    involves both the expression of a desire for political
    change and a discussion of the merits of the pro-
    posed change. Although a petition circulator may not
    have to persuade potential signatories that a particu-
    lar proposal should prevail to capture their signa-
    tures, he or she will at least have to persuade them
    that the matter is one deserving of the public scrutiny
    and debate that would attend its consideration by the
    whole electorate. This will in almost every case
    involve an explanation of the nature of the proposal
    and why its advocates support it. Thus, the circula-
    tion of a petition involves the type of interactive
    communication concerning political change that is
    appropriately described as “core political speech.”

Id. at 421-22.

   The Court recognized that a wholesale prohibition of paid
petition circulators limited such “core political speech” in two
ways: (1) “it limits the number of voices who will convey
[plaintiffs’] message and the hours they can speak and, there-
fore, limits the size of the audience they can reach”; and (2)
“it makes it less likely that [plaintiffs] will garner the number
of signatures necessary to place the matter on the ballot, thus
limiting their ability to make the matter the focus of statewide
discussion.” Id. at 423-424. The Court rejected Colorado’s
argument that the prohibition was justified by the state’s inter-
1882                   PRETE v. BRADBURY
est in protecting the integrity of the initiative process, reason-
ing that Colorado presented no evidence that paid petition
circulators are more likely to accept fraudulent signatures
over those of a volunteer, and that other Colorado statutes
prohibited accepting forged or fraudulent signatures. Id. at
426-27. The Court thus concluded the prohibition “imposes a
burden on political expression that the State has failed to justi-
fy,” and hence the prohibition violated the First Amendment.
Id. at 428.

    Similarly, in Buckley the Supreme Court struck down a
Colorado statute which required: (1) petition circulators be
registered voters in Colorado; (2) petition circulators wear an
identification badge bearing the circulator’s name; and (3) ini-
tiative proponents publicly disclose the names and amounts
paid to all paid circulators. 525 U.S. at 186. First, the Court
observed the registered voter requirement “decreases the pool
of potential circulators as certainly as that pool is decreased
by the prohibition of payment to circulators. Both provisions
limit the number of voices who will convey the initiative pro-
ponents’ message and, consequently, cut down the size of the
audience proponents can reach.” Id. at 194-95 (internal quota-
tion marks and alterations omitted). The Court rejected Colo-
rado’s assertion that the registered voter requirement was not
a severe burden because it was not difficult to register to vote;
although failure to register sometimes results from ignorance
or apathy, the decision not to register can also implicate “po-
litical thought and expression.” Id. at 195-96. The Court also
struck down the name badge requirement and the disclosure
provisions, explaining that both provisions forced circulators
to surrender the anonymity enjoyed by their volunteer coun-
terparts and had only a tenuous relationship to Colorado’s
interest in ensuring the integrity of the initiative process. Id.
at 198-204.

  Unlike Meyer, Measure 26 does not completely prohibit the
payment of initiative-petition circulators. Instead it prohibits
one method of payment. Plaintiffs claim that Measure 26 in
                       PRETE v. BRADBURY                     1883
practice limits the available pool of people willing to circulate
petitions. To the extent Meyer may be read to indicate that
any resulting decrease in the pool of available circulators is
sufficient to constitute a “severe burden” under the First
Amendment, in Buckley the Court refined its analysis and
made clear that the degree of the decrease resulting from the
measure is properly considered in determining the severity of
the burden. See id. at 192 (analyzing the degree of the effect
of the challenged provisions on the pool of available circula-
tors and explaining: “We therefore detail why we are satisfied
that, as in Meyer, the restrictions in question significantly
inhibit communication with voters about proposed political
change, and are not warranted by the state interests . . .
alleged to justify those restrictions.”) (emphasis added).

   Unlike Buckley, where the pool was limited to state resi-
dents registered to vote, here, anyone may serve as a petition
circulator, regardless of residence or registration. Therefore,
we find the Eight Circuit’s analysis of a North Dakota state
law more analogous to Measure 26, and thus more persuasive.
In Initiative & Referendum Inst. v. Jaeger, 241 F.3d 614 (8th
Cir. 2001), the Eighth Circuit distinguished North Dakota’s
prohibition on paying initiative-petition circulators “on a basis
related to the number of signatures obtained” (i.e., the same
type of restriction at issue here) from the complete prohibition
on paid petition circulators in Meyer. In Jaeger, the court
noted that the state had an “important interest in preventing
signature fraud” in the initiative process, and that the state had
supported that interest with evidence that paying petition cir-
culators per signature encouraged such fraud. Id. at 618. Fur-
ther, the plaintiffs had “produced no evidence that payment by
the hour, rather than on commission, would in any way bur-
den their ability to collect signatures. The [plaintiffs] have
only offered bare assertions on this point.” Id. Thus, because
the state asserted an important interest in preventing signature
fraud, supported that interest with evidence that signature
fraud was actually a problem in North Dakota, and the plain-
tiffs failed to present evidence the restriction would otherwise
1884                   PRETE v. BRADBURY
burden their ability to collect signatures, the court upheld the
ban on paying petition circulators on the basis of the number
of signatures collected. Id. For reasons discussed further
below, our case is more properly analyzed under the frame-
work applied in Jaeger than under Meyer or Buckley.

             A.   “Severe” or “Lesser” Burden

   Plaintiffs contend Measure 26 imposes a severe burden on
the circulation of initiative petitions because the measure
makes paid signature gathering prohibitively expensive, inef-
ficient, and results in a higher rate of invalid signatures. Plain-
tiffs thus contend that strict scrutiny should apply and
Measure 26 is not narrowly tailored to serve a compelling
governmental interest. The district court rejected this argu-
ment, finding plaintiffs did not prove that Measure 26
imposed severe burdens on the circulation of initiative peti-
tions, and any lesser burdens imposed by Measure 26 were
reasonably related to and justified by the state’s interest in
preventing fraud in the initiative process.

   In reaching that conclusion, the district court assessed
plaintiffs’ claims that: (1) Measure 26 eliminates an avenue of
signature-gathering and decreases the available pool of peti-
tion circulators; (2) Measure 26 increases the costs of gather-
ing signatures, making it more difficult to circulate petitions
and qualify initiative or referendum measures for the ballot;
and (3) Measure 26 resulted in a significant decrease in the
number of valid signatures collected by signature gatherers.
Because these are claims of historical fact, we review the dis-
trict court’s findings regarding these claims for clear error.
See Planned Parenthood, 290 F.3d at 1070. Because the dis-
trict court did not clearly err in rejecting each of these claims,
we affirm the district court’s holding that Measure 26 imposes
only a lesser burden on the circulation of initiative petitions.
                          PRETE v. BRADBURY                           1885
       1.   The Effect Of Measure 26 On The Pool of
                 Petition Circulators in Oregon

   Plaintiffs presented affidavits from William Arno of Arno
Political Consultants (“APC”), a California petition circula-
tion firm, and Tracy Taylor of Taylor Petition Management,
LLC, a Washington state petition circulation firm (under con-
tract with APC). Arno averred Measure 26 “make[s] it less
likely that companies such as APC will continue to do busi-
ness in Oregon” and stated he had “personal knowledge that
at least three of [his] chief competitors will not do business
in Oregon” because of Measure 26. Yet Arno later testified
that his “personal knowledge” of those companies came only
from Taylor.

   Taylor averred that several professional petition circulators
he knew were not interested in working in Oregon on an
hourly wage basis when they could work in other states on a
per-signature basis. Yet he did not identify those circulators,
nor state whether they would work in Oregon absent Measure
26. Indeed, both Arno and Taylor conceded that other factors
might cause petition circulators to leave or not to work in
Oregon. For example, Arno noted that access to private prop-
erty for petition circulators was particularly strict in Oregon.
Both Arno and Taylor also noted that “harassment” of paid
petition circulators by the Voter Education Project20 discour-
  20
     The Voter Education Project (“VEP”) bills itself as an “educational
watchdog organization” organized to protect the integrity of the initiative
system. It researches potential fraud and forgery committed by paid signa-
ture gatherers. It makes direct contact with voters through its “Think
Before You Ink” program, which informs voters that petition circulators
paid by the signature use devious tactics and commit fraud and forgery
during the collection of signatures. The record also includes a news article
that VEP also engages in harassment of paid petition circulators, “yelling
at them, threatening them, even following them in cars.” The article also
states VEP has links to the AFL-CIO. Other than the news article, plain-
tiffs presented no evidence that the VEP (or the Oregon AFL-CIO) sup-
ported Measure 26 to weaken in some manner the initiative process in
Oregon.
1886                  PRETE v. BRADBURY
aged some companies from working in Oregon. Last, Arno
also suggested that Measure 26 makes it more difficult for
petition circulation companies to operate because those com-
panies have to treat petition circulators as employees rather
than independent contractors. Yet Oregon employment law
requires that petition circulators must be treated as employees
rather than independent contractors; Measure 26 does not
itself mandate such treatment. See Canvasser Services, Inc. v.
Employment Dep’t, 987 P.2d 562, 568 (Or. Ct. App. 1999)
(holding, under Oregon law, petition circulators are employ-
ees rather than independent contractors).

   The district court rejected Arno and Taylor’s averments of
circulators leaving or refusing to work in Oregon as “unsup-
ported speculation” because Arno received his information
from Taylor, Taylor only repeated the basic claim that paid
circulators would not work in Oregon because of Measure 26,
and several factors other than Measure 26 could explain the
alleged reluctance of petition circulators to work in Oregon.
The district court’s factual conclusion is supported by the
record and is not clearly erroneous.

   Plaintiffs also presented affidavits from David Rubin of
Universal Petitions, a southern California petition circulating
firm; Lura Lucille Cordes, who employs initiative-petition cir-
culators to gather signatures in California; and Angelo Papa-
rella of Progressive Campaigns, Inc., a national signature
gathering firm. Rubin averred that because—in his opinion—
payment by signature is more efficient than payment by the
hour, and Measure 26 would thus make signature gathering
more difficult in Oregon, he is “sure I would never be asked
to go to Oregon to coordinate a petition drive with Measure
26 restrictions in effect.” Similarly, Cordes stated because of
the burdens imposed by Measure 26, she would “not come to
Oregon to circulate petitions/gather signatures.” Paparella
also stated that because of Measure 26, his company “will not
circulate petitions in Oregon because the cost of hiring and
maintaining a workforce of hourly wage workers is very, very
                      PRETE v. BRADBURY                    1887
high when compared to using petition circulators who are
independent contractors.” Yet none of these affiants stated
they had ever circulated petitions in Oregon or would do so
in the absence of Measure 26. Further, Paparella’s averment
suggests he would not come to Oregon because he would
have to treat petition circulators as employees rather than as
independent contractors, which is the law in Oregon notwith-
standing Measure 26. Therefore, the district court’s conclu-
sion that plaintiffs did not prove Measure 26 “caused a
reduction in the number of available circulators or otherwise
limit[ed] the size of plaintiff’s audience” is supported by the
record and is not clearly erroneous.

     2.   The Effect Of Measure 26 On The Cost of
             Signature Gathering in Oregon

   Arno averred that Measure 26 would increase the cost of
signature collection by 35-45 percent. Taylor similarly
averred Measure 26 would increase the cost of gathering sig-
natures in Oregon. Yet both Arno and Taylor based their pre-
dictions on the misapprehended fact that Measure 26
converted circulators from independent contractors into
employees, resulting in increased payroll costs. As noted
above, Oregon law recognizes petition circulators as employ-
ees, rather than independent contractors, notwithstanding
Measure 26.

   Further, Arno and Taylor had little, if any, experience in
initiative-petition circulation in Oregon before Measure 26
was passed. Arno testified he had worked on one initiative
campaign in Oregon “around 1992,” but that campaign
“ended up folding prior to turning in signatures.” Arno had
not worked on any other initiative campaigns in Oregon. Sim-
ilarly, Taylor testified that apart from an unrelated petition
(Referendum Petition 401 placed on the November 2004 bal-
lot), he had never worked on any initiative campaigns in Ore-
gon before or after Measure 26 was passed. Thus, as noted by
the district court, neither Arno nor Taylor could “offer a reli-
1888                       PRETE v. BRADBURY
able comparison on the added costs, if any, imposed by Mea-
sure 26.”

   Plaintiffs submitted several other affidavits which they con-
tend support their claim that Measure 26 poses a severe bur-
den by increasing costs. Jason Williams (one of the plaintiffs)
averred he did not circulate an initiative petition “due in large
part to the fact that the cost of circulating the petition, using
paid signature gatherers, has increased significantly.” Yet
Williams does not aver that Measure 26 is responsible for any
such price increase. R. Russell Walker, chief petitioner for an
unrelated initiative (initiative petition 59), averred that he did
not circulate that petition “due in large part to the fact that the
cost of circulating the petition, using paid signature gatherers,
has increased significantly.” Similarly, he makes no averment
that Measure 26 is to blame.

   The district court ultimately concluded “Measure 26
imposes no appreciable burden in terms of costs for an initia-
tive or referendum campaign.”21 Implicit in this finding is the
  21
    In making that finding, the district court also looked to an affidavit by
Ted Blaszak of Democracy Resources of Oregon, Inc., a signature gather-
ing firm. The Blaszak affidavit was submitted by intervenor-defendants.
Blaszak had run the signature gathering campaign for Measure 26, during
which the petition circulators were paid by the hour, not per-signature.
Blaszak averred that he had worked on about ten other initiative cam-
paigns in Oregon, and “the requirement to pay employees by the hour
rather than by the signature has not significantly increased my costs or
decreased productivity.”
   As noted in Section I, although the district court erred in granting
intervenor-defendants’ motion to intervene, that error was harmless. The
Blaszak affidavit supports defendant’s position that Measure 26 does not
increase the costs of initiative petition circulation, yet the district court
largely found that plaintiffs, through their own offer of proof, did not
prove that Measure 26 would impose such a burden. According to its
amended opinion and order, the district court did not rely upon any other
evidence submitted by intervenor-defendants. Thus, the district court’s
consideration of the Blaszak affidavit does not make it more probable than
not that the district court’s error in granting intervention tainted the ver-
dict. Furthermore, there is no evidence that defendant would not have
obtained and submitted the Blaszak affidavit if Nesbitt and the Oregon
AFL-CIO had not intervened.
                       PRETE v. BRADBURY                     1889
conclusion that Measure 26 does not substantially increase the
cost of initiative-petition circulation. This finding is supported
by the record and is not clearly erroneous.

3.   The Effect of Measure 26 On The Invalidity Rate of
      Signatures Gathered for Initiatives in Oregon

   Arno averred he “noticed a significant decrease in the num-
ber of valid signatures collected by signature gatherers since
Measure 26 became law.” Taylor similarly averred he “dis-
covered a disproportionate number of signatures to be invalid
[in Oregon], as opposed to the validity rates I am encounter-
ing in Washington and Ohio [which states do not prohibit
payment by signature].” Yet Taylor does not attribute the
higher invalidity rate to Measure 26 or suggest any reason for
the higher invalidity rate. He stated, however, that signature
gatherers paid by the hour “have more of an incentive to
defraud me [compared to signature gatherers paid per signa-
ture] because they know that regardless of whether I think the
signatures are valid, the signature gatherer must still be paid
an hourly wage.” As the district court noted, however, both
Arno and Taylor testified they had limited to no experience in
initiative and referendum processes in Oregon. Thus, their
assertions that paying petition circulators by the hour, instead
of per signature, results in higher signature invalidity rates
carry little weight.

   Both Williams and Walker also averred Oregon had a
higher signature invalidity rate post-Measure 26. Yet neither
affiant attributed the higher invalidity rate directly to Measure
26.

   In contrast, defendant submitted an affidavit from Richard
J. Ellis, Ph.D., a political science professor at Willamette Uni-
versity in Oregon. Ellis averred that “the available evidence—
though limited—suggests that circulators paid by the hour
also have a higher validity rate than those paid by the signa-
ture.” For example, in Oregon’s 2002 election year, Measure
1890                   PRETE v. BRADBURY
26 (which used only circulators paid by the hour) had a signa-
ture validity rate of 73.43 percent, higher than the ten other
initiative petitions submitted for that election. Ellis also states
the overall signature validity rates have dropped in Oregon
not because of Measure 26, but because a March 2000 direc-
tive by the Oregon Elections Division instructed county clerks
(who confirm the validity of signatures on petitions) not to
count initiative signatures by “inactive voters” (i.e., voters
who have registered but have not voted in a certain number
of past elections).

   Further, Referendum Petition 401, which was qualified for
the February 2004 Oregon ballot, after the passage of Mea-
sure 26, had a signature validity rate of 84.55 percent. Arno,
Taylor, and Williams were involved in the circulation and
gathering of signatures for Referendum Petition 401. The high
validity rate of the collection of signatures for Referendum
Petition 401, conducted after the adoption of Measure 26,
weighs against plaintiffs’ claim. The record, therefore, sup-
ports the district court’s conclusion that Measure 26 results in
higher validity rates for signature collection, rather than lower
validity rates. Therefore, the district court’s finding is not
clearly erroneous.

   In sum, plaintiffs’ presentation of proof falls short here.
The district court did not clearly err in finding that Measure
26 did not decrease the pool of petition circulators in Oregon;
did not increase the costs of signature gathering; and did not
result in a higher invalidity rate of signatures gathered for ini-
tiatives.

   We next review the district court’s determination that Mea-
sure 26 creates only a “lesser burden” on plaintiffs’ First
Amendment rights. Because this question relates to a constitu-
tional fact (i.e., what constitutes a “severe burden” or a “lesser
burden”), we review the district court’s determination de
novo. See Planned Parenthood, 290 F.3d at 1070.
                          PRETE v. BRADBURY                          1891
   As noted supra, the district court did not clearly err in find-
ing plaintiffs failed to prove Measure 26 resulted in any bur-
den on their First Amendment rights. Unlike Meyer, plaintiffs
did not prove that Measure 26 limited “the number of voices
who will convey [plaintiffs’] message and the hours they can
speak”; that Measure 26 “limits the size of the audience
[plaintiffs’] can reach”; or that Measure 26 makes it “less
likely that [plaintiffs] will garner the number of signatures
necessary to place the matter on the ballot, thus limiting their
ability to make the matter the focus of statewide discussion.”
See Meyer, 486 U.S. at 423-24. Moreover, unlike Buckley,
plaintiffs did not prove that Measure 26 significantly limits
the available pool of people willing to circulate petitions or
constrains petition circulators’ “political thought and expres-
sion.” See Buckley, 525 U.S. at 194-96.

   Of course, from an economic perspective, eliminating one
method of payment (but not every method, a la Meyer) for
petition circulators could result in some barriers to entry in the
signature procurement market. For a task like signature gath-
ering, it is possible that paying per signature (i.e., a commis-
sion basis) can be more productive of signatures than paying
an hourly wage. Whether Measure 26 creates such barriers to
entry, however, is a question of historical fact reviewed for
clear error.22 Here, the district court did not clearly err in find-
ing plaintiffs failed to prove the existence of such barriers to
entry or that, if present, they diminished petition circulators’
ability to garner the requisite number of signatures to qualify
initiatives for the ballot. Absent proof that such barriers to
entry existed and had the claimed result, we are not left with
a “definite and firm conviction that a mistake has been made”
by the district court. See Sawyer v. Whitley, 505 U.S. 333, 346
n.14 (1992); SEC v. Rubera, 350 F.3d 1048, 1093 (9th Cir.
2003) (citing Easley v. Cromartie, 532 U.S. 234, 242 (2001))
  22
    Whether the proven barriers, if any, constitute a severe or lesser bur-
den is a question of constitutional fact reviewed de novo. See Planned
Parenthood, 290 F.3d at 1070.
1892                      PRETE v. BRADBURY
(“Under the clearly erroneous standard, we defer to the lower
court’s determination unless, based on the entire evidence, we
are possessed of a ‘definite and firm conviction that a mistake
has been committed.’ ”).23

   Moreover, even if such barriers to entry did arise, they
would result in only a “lesser burden” under the First Amend-
ment. Measure 26 is quite limited in its proscription, barring
only payment of petition circulators on the basis of the num-
ber of signatures gathered. It does not prohibit adjusting sala-
ries or paying bonuses according to validity rates or
productivity, see Or. Admin. R. 165-014-0260, which could
likely counter any barriers to entry.

   In the absence of proof that Measure 26 creates such barri-
ers to entry or otherwise burdens their First Amendment
rights, plaintiffs have established only that Measure 26
imposes “lesser burdens” upon the initiative process. Gener-
ally, the finding of a “lesser burden” triggers a “less exacting
review” under which an “important regulatory interest[ ]” will
support a finding that the measure is a “reasonable, nondis-
criminatory restriction[ ].”24 See Bayless, 320 F.3d at 1007.25
  23
      “To be clearly erroneous, a decision must strike us as more than just
maybe or probably wrong; it must . . . strike us as wrong with the force
of a five-week-old, unrefrigerated dead fish.” Hayes v. Woodford, 301
F.3d 1054, 1067 n.8 (9th Cir. 2002) (citing Fisher v. Roe, 236 F.3d 906,
912 (9th Cir. 2001) (quoting Parts & Elec. Motors, Inc. v. Sterling Elec.,
Inc., 866 F.2d 228, 233 (7th Cir. 1988))).
   24
      “The ‘principal inquiry’ in determining whether a regulation is
content-neutral or content-based ‘is whether the government has adopted
the regulation because of agreement or disagreement with the message it
conveys.’ ” Crawford v. Lungren, 96 F.3d 380, 384 (9th Cir. 1996) (quot-
ing Turner Broadcasting Sys., Inc. v. FCC, 512 U.S. 622, 642 (1994))
(internal alterations omitted). “[L]aws that by their terms distinguish
favored speech from disfavored speech on the basis of the ideas or views
expressed are content-based.” Id. Here, Measure 26 does not regulate what
can be said in an initiative or referendum petition, nor does it adopt or
reject any particular subject that can be raised in a petition. It may be
                            PRETE v. BRADBURY                            1893
       B.    Oregon’s “Important Regulatory Interest”

  Defendant has an important regulatory interest in prevent-
ing fraud and its appearances in its electoral processes. See
Bayless, 320 F.3d at 1013; see also Timmons, 520 U.S. at 364

argued that a restriction on the initiative process itself, which is a means
to wrest power from the legislature, is inherently content-based. This argu-
ment must fail because in Oregon the initiative power may be used to
amend the constitution to grant additional power to the legislature. See Or.
Const. Art. IV § 1. See also Stranahan v. Fred Meyer Inc., 11 P.3d 228,
242 (Or. 2000) (“In sum, the case law demonstrates that Article IV, sec-
tion 1, confers an unfettered right to propose laws and constitutional
amendments by initiative petition, and to approve or reject such proposed
laws or amendments through the voting process.”); Bernstein Bros. Inc. v.
Dept. of Revenue, 661 P.2d 537, 539 (Or. 1983) (“The power to invoke
a referendum is a constitutional power reserved by the people. The cre-
ation of the referendum power (along with the initiative power) changes
the allocation of legislative power within a state, because after this cre-
ation the legislative power is shared between the people and their repre-
sentatives.”); Zilesch et al. v. Polk County et al., 215 P. 578, 582 (Or.
1923) (“[T]he legislature and the people, through the initiative or referen-
dum, [are] coordinate legislative bodies, and [ ] either [may] indepen-
dently repeal an act passed by the other . . . .”).
   25
      Plaintiffs alternatively contend that Measure 26 is subject to strict
scrutiny because it is content-based, in that it applies only to initiative and
referendum petitions, not to recall or candidate sponsorship petitions. See
Bayless, 320 F.3d at 1009 (noting strict scrutiny automatically applies to
content-based restrictions). The district court rejected this argument, not-
ing “the content of an initiative petition itself is not restricted, regulated
or otherwise affected by Measure 26.” We agree with the district court.
“The ‘principal inquiry’ in determining whether a regulation is content-
neutral or content-based ‘is whether the government has adopted the regu-
lation because of agreement or disagreement with the message it con-
veys.’ ” Crawford, 96 F.3d at 384 (quoting Turner Broadcasting Sys., Inc.
v. FCC, 512 U.S. 622, 642 (1994)) (internal alterations omitted). “[L]aws
that by their terms distinguish favored speech from disfavored speech on
the basis of the ideas or views expressed are content-based.” Id. Measure
26 does not regulate what can be said in an initiative or referendum peti-
tion, nor does it adopt or reject any particular subject that can be raised
in a petition. Therefore, Measure 26 is not a content-based restriction and
strict scrutiny does not apply.
1894                      PRETE v. BRADBURY
(“States certainly have an interest in protecting the integrity,
fairness, and efficiency of their ballots and election processes
as means for electing public officials.”). Further, the record
supports the conclusion that Measure 26 is aimed at combat-
ing actual instances of fraud and forgery committed by peti-
tion circulators paid on the basis of the number of signatures
gathered.

   First, the voter pamphlet circulated to the voters in consid-
eration of Measure 26 supports the conclusion that Measure
26 is aimed at combating fraud in the signature gathering pro-
cess. See Ecumenical Ministries v. Oregon State Lottery
Comm’n, 871 P.2d 106, 111 n.8 (Or. 1994) (“In considering
the history of a constitutional provision adopted through the
initiative process, [Oregon courts] examine[ ], as legislative
facts, other sources of information that were available to the
voters at the time the measure was adopted and that disclose
the public’s understanding of the measure . . . [such as] the
ballot title and arguments for and against the measure
included in the voters’ pamphlet . . . .”). The voter pamphlet
states in support of Measure 26 that “[t]his most recent elec-
tion cycle saw convictions [of paid petition circulators] on a
variety of forgery, fraud, and identity theft counts, charges
pending against others and allegations of dozens more.” Mea-
sure 26 would combat such fraud, the pamphlet states, by
removing the “incentive for fraud out of the system” by man-
dating hourly pay rather than per signature.

   As evidence of the actual existence of fraud and forgery in
the initiative process, defendant presented an affidavit from
Bill Carroll, a criminal investigator in the Oregon Department
of Justice. He averred that paying petition circulators per sig-
nature leads to two types of fraud. First, the signature gather-
ers often forge signatures, thus receiving payment for a
collected signature even though the signature is invalid. Sec-
ond, the signature gatherers falsely certify the petition signa-
ture sheets,26 either for petitions submitted by themselves or
for other petition circulators.
  26
   Petition circulators must certify that the signatures on the petitions
were obtained in the presence of the circulator and that upon belief, each
                            PRETE v. BRADBURY                            1895
   As attachments to his affidavit, Carroll supplied reports of
interviews of various signature gatherers (paid per signature)
who had forged signatures on their petitions; purchased signa-
ture sheets filled with signatures, then submitted them with
their petitions as if they had collected the signatures them-
selves;27 or participated in “signature parties” in which multi-
ple petition circulators would gather and sign each others’
petitions.28

   Defendant also submitted an affidavit by John Lindback,
Director of Oregon Secretary of State’s Elections Division.
He averred “the practice of paying signature gatherers by the
signature is a substantial case of . . . fraud” and forgery in the
initiative process.

  Plaintiffs point to the Arno and Taylor affidavits, however,
which aver that signature gatherers would not engage in fraud
or forgery

     because signature gatherers are “selling” each signa-
     ture to APC, and APC won’t “buy” a signature APC
     deems questionable. In that respect, signature gather-
     ers paid by the signature police themselves because
     professional signature gatherers don’t want a reputa-
     tion that would cause them to not be hired by APC
     in the future, or not be hired by other signature gath-
     ering companies.

signature is that of a registered Oregon voter. Or. Rev. St. § 250.045(7).
It is unlawful to make a false certification. Or. Rev. St. § 260.715(1).
   27
      Or. Rev. St. § 260.558(2) makes it unlawful “to sell, offer to sell, pur-
chase or offer to purchase, for money or other valuable consideration, any
signature sheet of an initiative, referendum or recall petition or any other
portion of the petition used to gather signatures.”
   28
      Or. Rev. St. § 260.555(3)-(4) makes it unlawful to obtain a signature
on an initiative “knowing that the person signing the petition is not quali-
fied to sign it”; or that the person has already signed the petition once.
1896                        PRETE v. BRADBURY
Although such a general proposition may be sound, it does
not controvert defendant’s evidence discussed above that
some signature gatherers paid per signature have engaged in
fraud and forgery, nor does it diminish defendant’s important
regulatory interest in preventing such fraud.29
  29
     Plaintiffs also rely on four district court cases. Those cases are distin-
guishable, however, because in each case the state defending the prohibi-
tion on per-signature payment for petition circulators failed to present any
evidence that per-signature payments increased fraud. Hence, in those
cases, the states presented no evidence to support their assertions that a
per-signature ban was necessary to promote the state interest in preventing
fraud and forgery in the initiative process. See Idaho Coalition United for
Bears v. Cenarrusa, 234 F. Supp. 2d 1159, 1165-66 (D. Idaho 2001) (the
plaintiffs challenged an Idaho prohibition making it a felony to “offer . . .
or attempt to sell . . . any petition or any part thereof or of any signatures”
for initiative petitions; the district court granted summary judgment for the
plaintiffs; construing the prohibition to prohibit payment of petition circu-
lators per signature, the court found Idaho presented no evidence of fraud
in the signature gathering process and thus struck down the prohibition as
violating the First Amendment); On Our Terms ’97 PAC v. Sec’y of State
of Maine, 101 F. Supp. 2d 19, 25-26 (D. Me. 1999) (the plaintiffs chal-
lenged Maine’s prohibition on paying petition circulators per signature;
following a bench trial, the district court ruled for the plaintiffs, finding
the prohibition burdened the signature gathering process but noting that
Maine provided “no evidence whatsoever that fraud is more pervasive
among circulators paid per signature, or even that fraud in general has
been a noteworthy problem in the lengthy history of the Maine initiative
and referendum process.”); Terms Limits Leadership Council, Inc. v.
Clark, 984 F. Supp. 470, 471 (S.D. Miss. 1997) (the plaintiffs challenged
a Mississippi prohibition on paying petition circulators per signature; the
district court granted summary judgment for plaintiffs, finding “plaintiffs
have shown that the[ ] statute[ ] burden[s] their right to political expres-
sion, [and] the State has failed to present evidence of fraud or actual threat
to its citizens’ confidence in government on account of the per-signature
payment of petition circulators.”); LIMIT v. Maleng, 874 F. Supp. 1138,
1140-41 (W.D. Wash. 1994) (the plaintiffs challenged Washington’s pro-
hibition on paying petition circulators on a per signature basis; the district
court granted summary judgment for the plaintiffs, finding Washington
presented “no actual proof of fraud stemming specifically from the pay-
ment per signature method of collection,” and thus Washington’s unsup-
ported interest in maintaining the integrity of the initiative process did not
outweigh the burdens imposed by the prohibition). Here, we have the affi-
davits of Carroll and Lindback, infra p. 1894-95.
                       PRETE v. BRADBURY                    1897
   [14] Like Jaeger, defendant asserted an important regula-
tory interest in preventing fraud and forgery in the initiative
process. Defendant supported that interest with evidence that
signature gatherers paid per signature actually engage in such
fraud and forgery. This court’s duty is not to determine
whether the state’s chosen method for prevention of fraud is
the best imaginable. Once the burden is found to be of the
“lesser” variety, our inquiry is limited to whether the chosen
method is reasonably related to the important regulatory inter-
est. Last, as the district court correctly determined, plaintiffs
did not prove Measure 26 would otherwise burden their abil-
ity to collect signatures. See Jaeger, 241 F.3d at 618.

   [15] In sum, because plaintiffs failed to prove the district
court erred in determining that Measure 26 does not severely
burden their First Amendment rights in circulating initiative
petitions, and defendant has established that Measure 26
serves the important regulatory interest in preventing fraud
and forgery in the initiative process, we hold that Measure 26
does not violate the First Amendment, as applied, and
AFFIRM the judgment of the district court.

  AFFIRMED.
