Maine Sen. Susan Collins, a Republican survivor, tries to defend seat against Democrat Troy Jackson

PORTLAND, Maine (AP) — Maine Republican Sen. Susan Collins, a moderate who is no stranger to difficult reelection campaigns, is seeking a sixth term Tuesday as Democrat Troy Jackson tries to help his party take control of the Senate for the rest of Donald Trump’s presidency.

Jackson is a former Maine Senate president who took over as the Democratic nominee in July after primary winner Graham Platner dropped out . He is tasked with defeating a longtime incumbent after a chaotic primary season that left the Democrats in disarray and briefly without a candidate.

It’s a race Democrats see as a top opportunity to flip a Republican-held seat. Maine has supported Democrats for president since 1992, and Collins is running for reelection at a moment when Trump is deeply unpopular.

But Democrats' bid to flip the seat hit setbacks. Party leaders in Washington initially backed Maine Gov. Janet Mills to run against Collins, only to see her fall flat while facing Platner in the primary. Platner overcame a wave of controversies, including the revelation of a tattoo recognized as a Nazi symbol, to win the nomination, only to drop out in July after facing an allegation of sexual assault that he denied.

Jackson was chosen as a replacement nominee during an emergency convention, and he had roughly 100 days to barnstorm the state trying to drum up support for his bid against one of the Senate's most influential members.

Collins, who is the sole remaining Republican lawmaker in Congress from New England, stressed her ability to deliver for Maine. She tried to distance herself from Trump, saying during a debate that she is “not exactly his favorite senator.”

Although Collins has shown a willingness to buck her own party and Trump, Jackson and other Democrats portrayed her as beholden to him and criticized her for caving to his wishes. Jackson hammered Collins on her vote to confirm Supreme Court Justice Brett Kavanaugh, a Trump nominee who eventually helped overturn constitutional protections for abortion . Collins, who supports abortion rights, has said she didn't regret her vote.

“Would you trust her to pick the next Supreme Court justice?” Jackson said during an October debate.

It could take a few days or longer before the winner is known, as Maine is one of two states with ranked choice voting. Collins and Jackson are the only candidates on the ballot, but write-in candidates could keep either from reaching 50% of the vote, in which case a ranked count would take place.

Collins, 73, was first elected in 1996 and is one of the most well-known figures in Maine politics. She grew up in the northern Maine city of Caribou where her family owns a sixth-generation lumber business. Collins worked for former Republican Sen. William Cohen for many years, starting when Cohen served in the U.S. House of Representatives, and would later succeed him in the Senate.

She has long touted her independence from Trump and her party. She has said she didn't vote for Trump in 2016, and she voted to convict the president after his 2021 impeachment over his role in the Jan. 6 Capitol riot .

When Vice President JD Vance made trips to Maine, Collins did not appear with him. Vance told the crowd at a May rally that he sometimes gets frustrated with the senator and wishes she were more partisan.

Collins has been a top target of Democrats before. She won handily in 2020 during a year that Democrats won the presidential race and both U.S. House seats in Maine.

During this year's race, Collins touted her longevity in the Senate and her status as a key player in powerful committees and budget negotiations. She said those aspects of her service remain critically important for Mainers.

“It has been 92 years since a Maine senator was chair of the Senate Appropriations Committee, the most powerful committee in the Senate,” Collins told reporters. “When I took over last year, I realized I had a once-in-a-century opportunity to help the state of Maine and pursue national priorities as well.”

Collins has also tried to highlight Jackson's temperament. Her campaign criticized Jackson for telling her to “shut up” during a debate.

Jackson, 58, initially ran for the Democratic nomination for governor and lost. He then won the nominating convention for Senate in July.

It made for a rushed start to the campaign for Jackson, a fifth-generation logger from rural far northern Maine. Since then, he has held events at churches, union halls and bars to tout issues such as workers' rights and fighting the high costs of housing and healthcare.

He has long had support among progressive Mainers, as he worked as independent Vermont Sen. Bernie Sanders' presidential campaign leader in Maine. At times, his campaign rhetoric is reminiscent of Sanders, who joined Jackson for rallies in October.

“In the end, if you work hard, you should be able to build a decent life,” Jackson said at a campaign event near Portland in September. “But that's not the reality right now.”

He criticized Collins as not doing enough to stop Trump. Jackson noted she voted to advance Trump's signature tax cut and budget legislation out of committee, before she was a “no” vote on its final passage.

“Sen. Collins is like an arsonist who helps set the fire and then she wants credit for bringing a cup of water to put it out,” he said.

Kruesi reported from Providence, Rhode Island.