LEWISTON — Though U.S. Sen. Susan Collins told Mainers she did not vote for Republican Donald Trump in the 2016 presidential race and disclosed she would not vote for him this year, she remains mum about the ballot she cast in 2020.

Maine’s senior senator, one of the longest-serving Republicans, declined recently to clarify whom she chose in the hard-fought presidential faceoff four years ago when Democrat Joe Biden defeated Trump.

That year, when Collins was locked in what appeared to be a tight reelection fight of her own, she steadfastly refused to say whether she would back her party’s presidential nominee, Trump, in his quest for a second term.

“At that point, I knew both the candidates,” Collins said after touring a Lewiston factory recently, “and I wanted to make sure that that relationship continued” no matter who won.

“It just seemed to be a better approach to focus on my own campaign,” she added.

But that campaign, in which Collins handily defeated Democrat Sara Gideon of Freeport, was over long ago. Pressed to disclose who she wound up voting for, Collins just smiled.

“Nice try, trying to get an exclusive,” she told a reporter. “That’s in the past. Let’s focus on the future.”

She refused to say more.

Last month during a visit to Auburn, Collins said she would not vote for Trump this year.

Instead, she said, she will write in former South Carolina Gov. Nikki Haley, who served as Trump’s ambassador to the United Nations, “because she’s still my favorite candidate, and I think she could do a great job.”

In 2016, Collins took a stand against Trump months before the balloting, staking out her position in a Washington Post op-ed in which she declared the former television show host “lacks the temperament, self-discipline and judgment required to be president.”

She initially said she wished the Libertarian Party had chosen former Massachusetts Gov. Bill Weld as its presidential candidate rather than its vice-presidential choice. She would vote for Weld if she could, the senator said.

But at the end of the 2016 campaign, unable to bring herself to vote for anyone on the presidential ballot, Collins said she wrote in former U.S. House Speaker Paul Ryan as her choice for president.

Neither Ryan in 2016 nor Haley in 2024 filed in Maine as a write-in candidate, so write-in votes for them would not have been counted.

As for Collins’ still-secret vote in 2020, some speculated online that she voted for Trump but doesn’t want to admit it. Others have said she likely voted for Biden, an old friend she once called “a breath of bipartisan fresh air.”

Several news stories in the past month, including one in the Sun Journal and one by the Associated Press, said Collins did not vote for Trump in 2020.

Given Collins’ stance, it’s impossible to say the stories were wrong. But it’s also clear they may have been incorrect.

The Associated Press did not cite a source for its assertion she did not vote for Trump. The Sun Journal’s assertion was based on a conversation with someone close to Collins who said Maine’s senator didn’t vote for Trump. But that individual said the claim was based on “knowing what she thought” rather than something more specific.

At this point, only the senator and those close to her whom she’s chosen to tell know for sure.