As Maine Democrats head to U.S. Senate primary, party anxieties center on Graham Platner

Maine Democrats are heading into a June 9 Democratic primary for a U.S. Senate nomination with new attention focused on whether voters will rally behind party establishment support for Graham Platner or instead cast what some Democrats are describing as a protest ballot, Politico reported June 5. The party’s central goal is to select a Democratic nominee positioned to challenge incumbent Republican Sen. Susan Collins in November.

The Democratic primary is scheduled for Tuesday, June 9, 2026, and is being held under Maine’s ranked-choice voting rules when three or more candidates qualify for the ballot, or when two candidates qualify and there is a declared write-in candidate in the race, according to Maine’s Secretary of State guidance. On the Democratic ballot for the Senate nomination, the listed candidates are David Costello and Graham Platner, according to Maine Public’s “Your Vote 2026” voter guide.

In recent days, a series of reports about Platner have widened concerns inside Democratic circles. On Friday, AP reported that Platner addressed a crowd in Bar Harbor and sought to blunt the impact of allegations and media reporting about his history with women, which the campaign has characterized as politically motivated and false. AP reported that last weekend his campaign dealt with stories about sexually explicit messages that Platner sent to several women while he was married, and that further reporting about his relationships had emerged during the week.

AP also reported that a separate new report included allegations from an ex-girlfriend describing incidents that, she said, involved physical grabbing and restraining during their relationship more than a decade earlier. In response, Platner told supporters that “When politically motivated, serious and false accusations are made against me, Maine, you have my back,” framing the controversy as inaccurate and part of a broader effort to discredit him.

Ahead of the primary, top Democrats have continued to engage with Platner. Reuters reported June 2 that Senate Democratic Leader Chuck Schumer met with Platner and said at a news conference that he had endorsed him, adding that Democrats would “beat Susan Collins and take back the Senate.” Reuters also reported that Platner was expected to win the June 9 Democratic nomination to face Collins, describing the race as a must-win for Democrats in the November midterms.

As the primary draws closer, the attention on voter enthusiasm is showing up in day-to-day campaign activity. AP reported on Sunday, June 7, that Platner was scheduled to take questions from voters at a town hall-style event in Portland, with the event taking place two days before the primary. The report said the pre-election scrutiny could offer clues about whether enthusiasm for his candidacy has softened enough to alter the outcome.

Maine’s ranked-choice system means Tuesday’s results could involve more than first-choice totals if multiple candidates and any declared write-ins are in play, with tabulation proceeding through ranked selections rather than a simple plurality. Whether Democrats describe it as a “protest vote” or a shift in support, the party’s nominee will be determined through the statutory voting and counting process, setting the stage for the general election contest against Collins later this year.