Maine Gov. Janet Mills (D) on Tuesday formally launched her bid to unseat Sen. Susan Collins (R-Maine), teeing up the latest high-profile primary to pit establishment and populist factions of the Democratic Party against each other.
Mills launched her campaign after much prodding from Senate Minority Leader Chuck Schumer (D-N.Y.). But prominent progressives like Sen. Bernie Sanders (I-Vt.) are backing oyster farmer and military vet Graham Platner.
Sanders has signaled he’s against Mills’s entry into the race, and there are concerns that the primary could turn bitter and potentially hurt the party’s chances of defeating a Republican they’ve long seen as vulnerable.
“I think she’s certainly the favorite. She’s the best known,” said James Melcher, a political science professor at the University of Maine at Farmington. “The national Democratic Party is pushing hard for both her and [Rep.] Jared Golden because they think they’re the more electable candidates of the group.”
At the same time, Melcher warned Mills was “not a slam-dunk certain-winner by any stretch.”
“I think a lot of Democrats in Maine feel like a conversation is needed about what direction will be taken in the future, and I think a lot of people all over the spectrum of the Democratic Party don’t think a primary would be a bad thing,” he added.
In Mills’s two-minute launch ad, she touted standing up to the president over the White House’s threats to withhold federal funding to the state for refusing to block transgender women from playing in women’s sports.
“We stood up to Trump and stopped him from cutting the school lunch program for Maine kids. But there are too many politicians in Washington — including Susan Collins — who have forgotten their principles and let bullies like Trump have their way. And it’s hurting Maine people,” she said in the ad. “I’ve never backed down from a bully and I never will.”
“This election will be a simple choice: Is Maine going to bow down or stand up?” she ended the ad by saying. “I know my answer.”
Mills’s allies tout the fact that she has won statewide in Maine, securing at least half of the vote during both of her gubernatorial elections. Prior to helming the state, Mills also served two terms as Maine attorney general and was also a district attorney for the Androscoggin, Franklin and Oxford counties.
“This moment demands someone with backbone and grit, someone who has proven she will fight Trump head on and defeat him when he tries to hurt Maine – that is Janet Mills,” EMILY’s List Jessica Mackler said in a statement, endorsing Mills.
Her entry adds to a crowded Democratic primary that includes Platner; fashion designer Natasha Alcala; military veteran and former Pentagon policy writer David Evans; former Army veteran Tucker Favreau; Maine Beer Company co-founder Dan Kleban; University of Maine professor Andrea LaFlamme; former contracting officer for the U.S. Air Force Daira Smith-Rodriguez; and Jordan Wood, a former chief of staff to former Rep. Katie Porter (D-Calif.).
“We know that the No. 1 thing that Democratic primary voters want right now is to win and having somebody who has managed to win with more than 50 percent multiple times statewide at the helm seems like a pretty good way to do that,” said Lanae Erickson, senior vice president for social policy, education and politics at the center-left Third Way.
Yet Sanders and some youth-focused Democratic groups have come out in support of Platner, who has focused his campaign on the working class and an economic populist message. And while he largely started out as a political unknown, he’s starting to be taken seriously after he raked in $4 million since he rolled out his campaign in August.
In a statement, Platner said he welcomed the governor’s entry to the race and touted that he hosted over 20 town halls across Maine.
“Everywhere I hear the same thing: people are ready for change,” Platner said. “They know the system is broken and they know that politicians who have been working in the system for years, like Susan Collins, are not going to fix it.”
Some view the race less as a proxy war between the mainstream vs. progressive factions of the party and more so as one between the establishment and those looking for newer, younger voices to take the helm. Others see it as a test case for who is better at meeting the moment as Democrats suffer low approval ratings.
“After our historic loss in the 2024 election, conversations within the Democratic Party have rightly centered on age, the loss of young men, the working class, and the growing disillusionment of young voters,” said Leaders We Deserve president and co-founder David Hogg in a statement. “As our party charts a path forward, Graham Platner represents not the entire solution, but a vital step in the right direction.”
“As someone who would be the second-youngest Democratic member of the U.S. Senate, and a leader with the courage and conviction this moment demands, we could not be more proud to endorse him,” Hogg added.
Voters of Tomorrow executive director Santiago Meyer said in his own statement that young people were “done settling for politics as usual.”
Those close to Mills dispute the notion she hasn’t been meeting the moment for Democrats in her state.
“The idea that Janet Mills is part of the mainstream establishment who is part of the problem and not delivering results for Maine people doesn’t line up with reality,” a person close to the governor told The Hill, noting her accomplishments on things like expanding Medicaid access and abortion access.
Democrats like Sanders have also expressed worries that Mills’s entrance could fuel a brutal primary.
“It’s disappointing that some Democratic leaders are urging Governor Mills to run. We need to focus on winning that seat & not waste millions on an unnecessary & divisive primary,” Sanders wrote on X last week.
Senate Republicans, meanwhile, would welcome such a dynamic after having to contend with a few of their own competitive primaries in states like Georgia and Texas.
Joanna Rodriguez, a spokeswoman for the Senate Republicans’ campaign arm, also pointed out Mills’s age in a statement, saying that the Maine governor “wants to be the oldest freshman Senator in American history after a record of failure that turned Maine into one of the weakest economies in New England.”
“No matter which Democrat emerges, we’re confident Mainers will continue to trust independent problem solver Susan Collins to keep delivering for them,” she added.
But Senate Democrats are signaling they believe Collins’s seat could be in reach this time.
“Susan Collins is uniquely vulnerable and her deep unpopularity is driven by her record of selling out Mainers — from being a decisive vote for the justices who overturned Roe v. Wade to working to enact Trump’s damaging agenda that hurts Mainers,” Maeve Coyle, a spokeswoman for the Senate Democrats’ campaign arm, said in a statement.
“In 2026, Democrats will flip this seat.”