President Trump’s impeachment trial got underway in the Senate on Tuesday and Sen. Susan Collins of Maine played a role in attempting to ensure that the rules governing the proceeding mirror as much as possible the Senate’s last impeachment trial, that of President Bill Clinton in 1999.

Early in the day, Collins was among a small group of Republican senators who pressured Senate Majority Leader Mitch McConnell to make last-minute changes to the impeachment rules.

The concerns raised by the moderate Republicans prompted McConnell to agree to spread out the 24 hours allotted for each side’s opening statements over three days instead of two, and permitted House evidence to be admitted automatically.

Collins saw the changes as a “significant improvement,” said her spokeswoman, Annie Clark.

“Senator Collins and others raised concerns about the 24 hours of opening statements in 2 days and the admission of the House transcript in the record,” Clark said. “Her position has been that the trial should follow the Clinton model as much as possible,” referring to the rules adopted during the Clinton impeachment.

My statement on the start of the impeachment trial: https://t.co/oRp9jZ3CbR pic.twitter.com/QxDiCTzxub

— Sen. Susan Collins (@SenatorCollins) January 21, 2020

Collins later voted with Republicans to table a motion by Democratic Senate Leader Chuck Schumer to subpoena documents and witnesses. She also issued a statement in which she reiterated her intent to follow the Clinton model, in which the Senate heard the case and asked questions before voting on whether to subpoena witnesses and documents.

“As I said last week, while I need to hear the case argued and the questions answered, I anticipate that I would conclude that having additional information would be helpful,” her statement said. “It is likely that I would support a motion to subpoena witnesses at that point in the trial just as I did in 1999.”

Maine’s other senator, independent Angus King, had sharply criticized the initial rules put forward by McConnell, including fewer days for opening statements and no automatic inclusion of House testimony.

“For weeks, Senator McConnell has been telling everyone who would listen that the Senate’s impeachment process would use the rules that governed the Clinton impeachment – but it is clear today that his assertions were at best misleading, and at worst, a willful bait and switch,” King said. “It is more obvious than ever that this is not just a trial in the Senate – it is a trial of the Senate. As we approach today’s votes, my colleagues and I face a stark choice: we can either commit to a fair trial that focuses on getting the truth, or endorse a flawed process that attempts to undermine our work before it’s even begun. If I have one bit of advice for my Senate colleagues, it is this: the truth will come out in all of this, and we will be judged on whether we sought it or sought to avoid it. I sincerely hope that our body can rise to this task, and live up to our shared commitment to impartial justice.”

After the changes, King’s spokesman, Matthew Felling, said he welcomed McConnell taking a step toward the senator’s position.

The impeachment trial, which centers on whether Trump abused his power by pressuring Ukraine to investigate a political rival, is expected to be a fiercely partisan affair. To remove the president from office, a two-thirds majority of senators would need to support it, a prospect that appears unlikely given the the Senate’s makeup of 53 Republicans, 45 Democrats, and two independents who caucus with Democrats.

However, Collins and a small group of Republicans could play a role in how much additional evidence and testimony could come forward.