Sen. Susan Collins Susan Margaret CollinsSenate Republicans face tough decision on replacing Ginsburg Democratic senator calls for eliminating filibuster, expanding Supreme Court if GOP fills vacancy What Senate Republicans have said about election-year Supreme Court vacancies MORE (Maine) became the only GOP senator to break with her party during a marathon session over the rules for the Senate's impeachment trial of President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE.

Democrats forced a 10th amendment vote early Wednesday morning that would extend the amount of time House impeachment managers and Trump's legal team have to respond to motions.

Currently, both sides can file motions around 9 a.m., including a potential motion to dismiss the charges against Trump. Under the rules, the opposing side would have to respond by 11 a.m. The amendment by Democrats would extend that time, giving them until Thursday to respond.

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A spokeswoman for Collins didn't immediately respond to a request for comment about why she broke with her party and voted against tabling the amendment.

The early morning vote came after the first nine amendment votes failed, with senators voting along party lines to table the proposals from Democrats, including attempts to subpoena former national security adviser John Bolton John BoltonDiplomacy with China is good for America The Hill's Morning Report - Sponsored by The Air Line Pilots Association - Pence lauds Harris as 'experienced debater'; Trump, Biden diverge over debate prep DOJ launches probe into Bolton book for possible classified information disclosures MORE and acting White House chief of staff Mick Mulvaney Mick MulvaneyMick Mulvaney to start hedge fund Fauci says positive White House task force reports don't always match what he hears on the ground Bottom line MORE.

But moderate Republicans have been able to flex their muscle in the early days of the trial. With Republicans passing the rules without help from Democrats, that gives any group of two or more senators the ability to try to force changes.

Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE (R-Ky.) needs 51 votes to pass the rules and Republicans have 53 seats.

The rules resolution initially only gave both parties two days to make opening arguments and did not automatically admit House evidence into the trial record.

But a group of GOP senators, including Collins, took issue with the provisions during a closed-door lunch. They were subsequently changed to give both sides three days and to have House evidence included in the trial record.

“Senator Collins and others raised concerns about the 24 hours of opening statements in two days and the admission of the House transcript in the record. Her position has been that the trial should follow the Clinton model as much as possible. She thinks these changes are a significant improvement,” Annie Clark, a spokeswoman for Collins, said on Tuesday.