Maine Gov. Janet Mills on Tuesday launched her much-anticipated challenge to Republican Sen. Susan Collins, landing Democratic leadership a prized recruit and likely setting up a generational test for the party in its quest to win back power in Washington. 

Mills joins a Democratic primary that already includes oyster farmer Graham Platner, who’s reported strong fundraising and picked up considerable progressive support. The Maine race is seen as Senate Democrats’ best pickup opportunity in 2026 as the only GOP-held seat in a state won by Kamala Harris last year.

“My life’s work has prepared me for this fight – and I’m ready to win,” Mills said in her announcement video. 

The video also features an exchange between Mills and President Donald Trump at the White House earlier this year, in which she told Trump, “See you in court,” in response to his threat to take away federal funding over noncompliance with his order to block transgender athletes from women’s sports.

“Honestly, if this president and this Congress were doing things that were even remotely acceptable, I wouldn’t be running for the U.S. Senate,” Mills said in her launch video. “But when Trump rips away health care from millions of Americans and drives up costs on everything from groceries to housing to trucks and cars, then turns around and gives corporate CEOs a massive tax cut … and Susan Collins helps him do it?”

Mills’ decision to run is a boon for Senate Democratic leader Charles E. Schumer, who had been encouraging her to join the race. Senate Democrats face an uphill climb to flip the four seats needed to win the majority next year, but party leaders see Mills, along with former Gov. Roy Cooper in North Carolina and former Sen. Sherrod Brown in Ohio, as top recruits in that effort. 

Unlike Cooper or Brown, Mills, 77, is poised to contend with a competitive primary that has already attracted more than half a dozen Democrats, who say a fresh face is needed to unseat Collins. 

Still, the Democratic primary field thinned Tuesday, with Dan Kleban, the co-founder of Maine Beer Company, ending his campaign and endorsing the governor.  

“While our message was right, the timing isn’t. Governor Mills is the right leader for this moment and is in the best position to win,” he said in a statement. 

Platner announced last week that his campaign had raised $4 million since launching in August, including more than $1 million raised in the first week of October. The 40-year-old already has the backing of Vermont Sen. Bernie Sanders and a coalition of youth Democratic organizations, and his campaign has touted the big crowds that have shown up to his town halls and other events. 

“In two months, we have built a movement together tens of thousands strong. We are not slowing down,” he said on social media Tuesday after Mills’ announcement. 

Sanders said on social media last week that it was “disappointing” that Democratic leaders were trying to recruit Mills: “We need to focus on winning that seat & not waste millions on an unnecessary & divisive primary.”

Also in the Democratic race is former House staffer Jordan Wood, who has held town halls across the state since launching his campaign in the spring. He said in a statement Tuesday that primaries were a “vital part of the democratic process” and called for primary debates in all 16 Maine counties.

“This campaign is about courage, accountability, and who has what it takes to defeat Susan Collins, defend our democracy, and deliver for working families,” he said in a statement. 

Wood’s campaign said he raised more than $3 million through Sept. 30, when the second quarter closed. Fundraising reports covering the three-month period are due to the Federal Election Commission before 12:01 a.m. on Thursday. 

A long political career

Mills is currently term-limited as governor and cannot seek reelection next year. A former state attorney general and state legislator, she won a second term in 2022, handily stopping a comeback bid from her Republican predecessor, Paul LePage. The former governor is challenging Democratic Rep. Jared Golden in Maine’s 2nd District next year. 

Mills’ decision to run for Senate was long anticipated, with an ActBlue fundraising page and related social media appearing prematurely ahead of her formal announcement.

If she wins, she would be the oldest freshman senator in history at 79. She told NBC News that she wouldn’t plan to serve for more than one term.

Mills’ entry also comes at a time when Democrats have grappled with questions of age after President Joe Biden pulled out of the presidential election last year. But she starts the race with strong institutional support within the party. 

“When we served as attorneys general together, I saw how Janet Mills stands up for Maine – taking on the big banks and drug companies, keeping families safe, and always putting Mainers first,” said Nevada Sen. Catherine Cortez Masto, a former chair of the Democratic Senatorial Campaign Committee. “She is a proven leader who knows how to win in Maine, and I’m excited to support her.”`

The DSCC and Mills’ campaign have formed a joint fundraising committee, according to an FEC filing.

Mills has appeared to have a collegial relationship with Collins. Earlier this year, the governor said that Collins was “in a tough position” when it came to pushing back on certain Trump administration policies and that she appreciated “everything she is doing.”

First elected in 1996, Collins chairs the powerful Senate Appropriations Committee and has the longest uninterrupted streak of consecutive roll call votes cast without missing a vote since the start of her Senate career and recently cast her 9,750th vote. 

While she has yet to formally announce her reelection bid, Collins, 72, has said she intends to seek a sixth term next year. Over her previous campaigns in the Democratic-leaning state, she  has proved adept at winning over crossover support. During her most recent campaign, in 2020, she defeated Democrat Sara Gideon, the Maine House speaker, by 9 points, prevailing on the first ballot without needing to use the state’s ranked choice process.

Her campaign had $5.3 million in the bank at the end of June. 

“The only thing Mills has gotten right in her career is praising Senator Susan Collins’ effective and proven leadership,” Alex Latcham, the executive director of the Republican super PAC Senate Leadership Fund, said in a statement. “So while Democrats fight among themselves, Senator Collins will keep doing what she’s always done — delivering for Maine families.”

Inside Elections with Nathan L. Gonzales rates the race Tilt Republican.

This story has been updated to reflect the year Mills defeated former Gov. Paul LePage.