Sen. Susan Collins, R-Maine, leaves the Senate chamber at the Capitol in Washington, Friday, Jan. 22, 2021. Credit: J. Scott Applewhite / AP

Susan Collins of Maine is part of a minority of U.S. senators who have yet to say how they will vote in former President Donald Trump’s second impeachment trial as the upper chamber faces an unprecedented decision on whether or how to sanction an ex-president.

Senators are set to be sworn in for the trial Tuesday, though the trial over allegations that Trump incited the Jan. 6 attack of the U.S. Capitol will not begin in earnest until February. Collins has voted against removing a president both times the question has faced her in the Senate — in 1999 when she broke with fellow Republicans to acquit Bill Clinton and last year when she stuck with all but one member of her party to clear Trump.

Her criticism of Trump over the attack has been among her sharpest since he first ran for office. She immediately faulted the president for the events and said in a Bangor Daily News Op-Ed that he “incited” rioters — the same language used in the House’s impeachment article a few days later. In another column co-written with Sen. Jeanne Shaheen, a Democrat from New Hampshire who backs removal, Collins condemned “threats to our democratic republic.”

She has also left procedural avenues open for the president’s possible acquittal, telling Maine Public this month that she thought the House moved too quickly to impeach him. She has not weighed in on the reasoning from some Republicans that the chamber should not be able to convict a president who is no longer in office.

Those conflicting hints are all we have as Collins’ decision not to comment on Trump’s potential removal ahead of the Senate trial — a routine approach that she took with his first impeachment — puts her in contrast with most senators. Seventy of 100 have come down one way or another on conviction, with 41 supporting it and 29 opposing it, according to a Washington Post tracker.

Sen. Angus King, an independent who caucuses with Democrats, announced his support for impeachment shortly before the House vote, calling Trump a “danger to the Republic,” though he said he would wait for evidence to be presented in the trial before formally deciding how to vote. While he remains one of the 30 undecided, he has gone much further than Collins to date.

The most commonly cited purpose of impeachment — removing an official from their position — is no longer relevant. A simple majority of senators could bar Trump from running for federal office again, but it appears that can only happen after a two-thirds majority votes to remove him. At least 17 Republicans would have to side with Democrats. If Trump were to be convicted, Collins would likely be among that group.

“She’s going to go about this with the same workmanlike effort that she goes about all of these significant, high-profile issues,” said Bobby Reynolds, a political operative who has worked for Collins in official and campaign roles.

Among the first considerations for Collins could be the argument from more than a dozen of her Republican colleagues that the Senate does not have jurisdiction over the trial with Trump no longer in office. That contention became more salient on Monday with the news that Chief Justice John Roberts would not preside over the trial under a constitutional reading that mandates the chief justice preside only over the impeachment trial of a sitting president.

Collins said in a statement that she has not ruled out legal issues associated with trying a president who had already left office, saying only that she was “considering” the issue and it would likely be resolved at the start of the trial.

“That is an issue that the Senate hasn’t addressed in the past,” she said.

The argument that the Senate would not have jurisdiction over a past president was “plausible” but the weight of the counterargument was “very, very strong,” said Frank Bowman, a University of Missouri School of Law professor who authored a book on impeachment.

He pointed to Congress’ ability to bar a president from running for office again after conviction as a way the framers intended to prevent popular demagogues from overthrowing democracy, and noted there was precedent for the Senate to try an official no longer in public office. It has not happened with a president, but it did with a former war secretary in the 1870s.

With Democrats in the Senate majority, there is little chance the impeachment case will be dismissed without a trial. After a two-week pause to give Trump’s legal team time to prepare, senators will judge the trial under the unique circumstance of also serving as witnesses to the Capitol riot with much of the evidence about the attack in the public eye.

Bowman characterized senators as not simply jurors but the “ultimate determiners of law and procedure,” noting there were no limits on the evidence or witnesses they could choose to introduce in the trial. But Collins, despite her criticism of the House impeachment procedure, said through her office that she thought it was important for the Senate to be “thorough” and “always believed” witnesses should be a part of the process.

“I hope that the House [managers] will carefully present their case so that the Senate has the best possible information upon which to render a judgment,” she said.