Graham Platner Emerges As Maine Democrats' Presumptive Senate Nominee, Urges Unity Against Susan Collins

PORTLAND, Maine — Graham Platner opened his remarks at the Maine Democratic Party convention Saturday night by thanking Gov. Janet Mills before addressing delegates about being the party's "presumptive nominee" for the U.S. Senate. His acknowledgment of Mills drew polite applause as the party pivoted quickly from a bruising primary fight to preparing for a difficult fall matchup against Republican Sen. Susan Collins.

Mixed Reaction From Delegates

Delegates at the biennial waterfront convention expressed a mix of relief, enthusiasm and concern. Jens Dill, a 72-year-old retired software engineer from Winthrop, said Mills' primary challenge helped Platner organize his campaign and push it forward. "She gave him enough challenge to get his campaign off the ground and organized, and she stepped down when she saw that it was time," Dill said. "And she sent a message to Susan Collins: This guy knocked me out of the race. You’re next."

Other delegates voiced skepticism. Bettie Harris-Howard, a 76-year-old retired nursing administrator from Winthrop, described Platner's speech as "filled with empty platitudes" and said she remains unsure whether she will vote in November. "I think Susan Collins is probably going to take it anyway," she said, citing the Republican Party's capacity to marshal heavy resources.

Controversies and GOP Attacks

Platner, an Iraq and Afghanistan veteran and oyster farmer, has faced scrutiny over past social media posts and a tattoo he later covered that some observers said resembled a Nazi symbol. Platner has said he was unaware of that association and has since covered the tattoo; he has also attributed earlier controversial comments to struggles related to post-traumatic stress.

Republicans have already begun targeting Platner. Pine Tree Results PAC, a GOP super PAC, released an ad highlighting his past posts and the tattoo, and party strategists say tens of millions could flow into the race. Platner has invited skeptical voters — including former Mills supporters — to raise those concerns at his town halls.

Ground Game and Party Unity

Platner is banking on a robust grassroots operation: his campaign says it has roughly 15,000 volunteers and a strong small-dollar fundraising program. Supporters at the convention credited that organizing effort with generating enthusiasm and argued it could be decisive against Collins.

"We are doing something entirely different, and that’s why we’re gonna win," Platner told NBC News after a rally, adding that voters must decide whether they believe he has changed.

Many delegates urged national and state Democrats to rally behind a unified message focused on defeating Collins in November. Some raised frustrations that national endorsements for Mills, including from Senate Minority Leader Chuck Schumer and the Democratic Senatorial Campaign Committee, did not bring substantial ad support in Maine.

National Voices And The Road Ahead

Minnesota Gov. Tim Walz, who spoke at the convention and is seen as a key national Democratic figure this year, framed the party’s internal debate as healthy. "These are healthy; the Democratic Party is willing to have discussions amongst themselves," Walz said, adding that Platner "is obviously capturing some energy." He predicted a favorable outcome for Democrats in Maine: "I think Maine is done."

Platner still must secure the Democratic nomination in the June 9 primary; former state official David Costello remains on the ballot. As the contest moves forward, Democrats face the twin tasks of consolidating support and preparing for a Republican-financed general election fight.

Disclosure: This article was adapted from reporting published on NBCNews.com.