A political action committee connected to U.S. Senate Majority Leader John Thune announced Tuesday an initial investment of $42 million in support of Republican Susan Collins in Maine’s U.S. Senate race.

The Senate Leadership Fund said in a news release that the initial investment is the largest it’s ever made in the state. It includes nearly $37 million for statewide broadcast, cable, digital and radio, as well as digital ads, direct mail, text messaging and get-out-the vote efforts.

“Senator Susan Collins’ incredible legislative accomplishments, unrelenting work ethic, and history of winning tough races against Washington Democrats is unmatched,” Executive Director Alex Latcham said.

Collins is widely viewed as the most vulnerable incumbent Senate Republican this cycle. Seeking her sixth term, she’s the only Republican up for election in a state won by Democrats in the 2024 presidential race. She also suffers from low approval ratings.

The announcement comes as Trump has publicly criticized Collins for supporting a resolution to further limit military action in Venezuela without congressional approval.

Trump blasted Collins and other Republican defectors after the recent vote, saying in a social media post that she “should never be elected to office again.”

Then, in a speech last week in Detroit, he called Collins and Sen. Lisa Murkowski, R-Alaska, both “disasters.”

Senate Republicans have a 53-47 majority. Collins is not facing a credible primary challenge from anyone in her own party.

Democrats, meanwhile, are focusing their efforts on seven states. In addition to Maine, the Democratic Senatorial Campaign Committee is eying pickup opportunities in Alaska, Iowa, Michigan, New Hampshire, North Carolina and Ohio.

“At the start of the election year, Democrats have created multiple paths to flip the majority in 2026,” the committee said in a Jan. 14 memo published by Punchbowl News.

Senate Minority Leader Chuck Schumer, D-N.Y., is credited with recruiting Maine Gov. Janet Mills to take on Collins. He also landed preferred candidates in Alaska, Ohio and North Carolina.

Tommy Garcia, spokesperson for Mills’ Senate campaign, said in a statement that the latest donation announcement shows how “Republicans and their billionaire backers are pulling out all the stops” for Collins.

Mills is locked in a competitive primary with political newcomer Graham Platner, an oyster farmer and combat veteran who has been endorsed by Sen. Bernie Sanders, a progressive icon from Vermont.

Schumer was bullish about Maine when he spoke to Punchbowl last week.

“My current sense is we’re going to win,” Schumer said. “Susan Collins is in a very weak, weak position, and Janet Mills has been a two-term governor, and she’s the only Democrat who has won statewide in 20 years.”

As of December, Maine’s Senate race was the fourth-most expensive in the country, according to AdImpact, which tracks political spending.

Collins was last reelected in 2020, a race that saw about $200 million in total spending, a study by America Promise found. The race was the second most expensive per vote that cycle, a Press Herald analysis found.

Despite trailing in the polls, Collins beat Sara Gideon, a Freeport Democrat and former speaker of the state House of Representatives, by 9 points.

Earlier this year, Politico reported that the National Republican Senatorial Committee predicted that both parties combined would spend between $400 million and $600 million on Maine’s Senate race.