Cascade County law enforcement agencies are investigating approximately 800 petition signatures that may be invalid, while Democratic U.S. House candidate Brian Miller has filed a lawsuit seeking to disqualify independent rival Michael Eisenhauer from the ballot. The legal challenge and criminal probe emerged as reported by montanafreepress.org, highlighting tensions in Montana’s Eastern Congressional District race just weeks before early voting begins.

The Cascade County Attorney’s Office and Sheriff’s Office are examining signatures gathered by petitioners working for independent candidates Michael Eisenhauer and Seth Bodnar. Eisenhauer is running for the U.S. House seat, while Bodnar is seeking Montana’s open U.S. Senate position. Investigators have not alleged that any of the signatures in question are fraudulent, nor do they suspect either campaign of wrongdoing. Both campaigns have cooperated with the inquiry.

Lawsuit Challenges Signature Validity

Brian Miller filed his lawsuit this week asking a judge to invalidate hundreds of signatures that counted toward Eisenhauer’s ballot qualification. Under Montana law, independent candidates must collect signatures from registered voters to appear on the general election ballot, whereas party-affiliated candidates qualify through primary elections.

Eisenhauer submitted 7,274 signatures before the May 26 deadline. Bodnar collected 13,327 signatures by the same date. Miller’s lawsuit does not challenge Bodnar’s eligibility but references his campaign in its filings.

The legal argument centers on affidavits signed by signature gatherers attesting to the validity of their batches. Miller contends that if even one signature in a batch is fraudulent, the entire affidavit should be invalidated. If successful, this approach could remove approximately 1,600 signatures from Eisenhauer’s total, dropping him below the required threshold for ballot access.

Miller also argues that any signature collected by a gatherer who submitted at least one fraudulent entry should be discarded. That broader interpretation could disqualify roughly 5,600 signatures associated with those petitioners.

Campaign Responses and Legal Timeline

Eisenhauer dismissed the lawsuit as “frivolous” and said it “represents a desperate move by Brian Miller.” The independent candidate has maintained that his signature collection efforts complied with state requirements.

Detectives are currently interviewing signature gatherers and individuals who claim their names were added to petitions without permission. Cascade County law enforcement has not publicly alleged large-scale fraud or identified any single forged signature as of the report’s publication.

Miller stated that if a judge rules in his favor, votes cast for Eisenhauer should not be counted in the general election. District Court Judge Mike McMahon will hold a scheduling conference on Monday to establish a timeline for resolving the lawsuit.

Election Context

The legal dispute unfolds as ballots went to the printer on Wednesday. Early voting is scheduled to begin October 6, giving limited time for judicial resolution before voters head to the polls.

Miller spoke at the 48th annual Mansfield Metcalf Dinner on March 7, 2026, in Helena, where he outlined his campaign platform and criticized independent candidates for splitting the opposition vote. The dinner is a longstanding Montana political tradition that brings together lawmakers, donors, and party activists.

The investigation remains ongoing. Cascade County officials have emphasized that signature gatherers, not candidates or campaigns, are legally liable for submitting fake signatures under state election law.