Sen. Susan Collins (R-ME) is taking on Senate Majority Leader Mitch McConnell (R-KY) over fairness in the upcoming impeachment trial of President Trump.

In an interview that aired Monday night on Maine Public Radio, Collins — a noted moderate among GOP conservatives — criticized McConnell for saying he is working in “total coordination” and “lockstep” with the Trump White House while preparing for the trial.

She criticized some Democrats, too — in particular Sen. Elizabeth Warren (D-MA) — for  “prejudging” the president.

“It is inappropriate, in my judgment, for senators on either side of the aisle to prejudge the evidence before they have heard what is presented to us, because each of us will take an oath, an oath that I take very seriously to render impartial justice. That’s what it says, impartial justice,” Collins said.

One key sticking point is the issue of calling witnesses in the Senate trial. Democrats, led by Sen. Chuck Schumer (D-NY) want to subpoena acting White House chief of staff Mick Mulvaney, former national security adviser John Bolton and others.

Again, Collins opposed McConnell’s position.

“I am open to witnesses,” she said, but added that “it’s premature to decide who should be called.”

Collins is the second GOP senator to criticize McConnell’s comments, notes NBC News: “Earlier this month, Sen. Lisa Murkowski of Alaska said she was ‘disturbed’ that the Senate majority leader said he was coordinating with the White House.” 

 Collins emphasized that the Trump trial should “should mimic the bipartisan approach taken against Clinton in the late 1990s,” says Newsweek.

“I have made that recommendation,” Collins said in the Monday interview. “I have spoken in our caucus … and I have shared with my colleagues my belief that the Clinton approach, the approach to the Clinton trial worked well.”

Collins’ views contrast sharply with those of most GOP senators.

Sen. Lindsey Graham (R-SC) vowed this month “to kill impeachment as soon as it reached the Senate,” Newsweek says.

“I am trying to give a pretty clear signal I have made up my mind. I’m not trying to pretend to be a fair juror here,” Graham said.

No date has been set for the start of the trial, largely because House Democrats have not yet sent to the Senate the articles of impeachment passed Dec. 18.