Sen. Mitt Romney speaks to journalists about the impeachment inquiry before the Senate weekly policy luncheons on Capitol Hill on Oct. 29. (Melina Mara/The Washington Post)

ON WEDNESDAY, as Senate Republicans prepared to acquit President Trump of abuse of power, Sen. Mitt Romney (R-Utah) offered a profile in courage. He announced he would vote to convict the president, becoming the only Republican to do so. Mr. Romney, alone, defied the partisanship and political incentives of the moment — and was willing to endure the punishment that is surely on its way — simply because he judged conviction to be the right call.

Mr. Romney’s reasoning was simple: The president is obviously guilty. “There’s no question that the president asked a foreign power to investigate his political foe,” he said Wednesday. “There’s not much I can think of that would be a more egregious assault on our Constitution than trying to corrupt an election to maintain power. And that’s what the president did.”

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Unlike many of his GOP colleagues, Mr. Romney refused to ignore the facts. “I don’t see how in good conscience I can reach a conclusion and not be true to what my heart and mind tells me is true,” he told the Deseret News shortly before his announcement.

Mr. Romney rejected on Wednesday the cynicism that has driven so many of his colleagues to avert their gaze from the roiling disaster of the Trump presidency. “He’s the president of the United States. I voted with him 80 percent of the time,” he said. “I agree with his economic policies and a lot of other policies. And yet he did something which was grievously wrong. And to say, well, you know, because I’m on his team and I agree with him most of the time, that I should then assent to a political motive, would be a real stain on our constitutional democracy.”

Mr. Romney’s choice promises him nothing but grief. Utah is deep red, and Mr. Trump carried it handily in 2016. Mr. Romney could have voted to acquit with political — if not moral — impunity. He would have avoided what is sure to be a sharp, sustained and personal backlash from Mr. Trump and his supporters.

From the archives: Mitt Romney: The president shapes the public character of the nation. Trump’s character falls short.

Other Republican senators flinched at that prospect. Lamar Alexander (Tenn.), a retiring senator from whom one could have expected more, would not even vote to hear from key witnesses such as former national security adviser John Bolton. In an interview with “PBS NewsHour,” Sen. John Thune (R-S.D.) couldn’t even bring himself to say whether he thought the president’s actions were right or wrong.

For those who believe in impeachment and those who don’t, Mr. Romney deserves respect for thoughtfully weighing the evidence and the implications of removing a sitting president. His stand did not persuade his GOP colleagues to reconsider. Fifty-two of them voted Wednesday to acquit the president on the abuse of power charge; Mr. Romney joined them in voting to acquit on the charge of obstruction of Congress. But Mr. Romney assured one outcome: No longer can Republicans argue that the Democrats forced on the nation a partisan impeachment that garnered not a single supporting GOP vote. At least one Republican acted with integrity and honor. History will remember the rest very differently.

Read more:

Jennifer Rubin: Mitt Romney shows us all is not lost

Greg Sargent: Mitt Romney’s stunning vote to convict Trump puts the GOP to shame

The Post’s View: It’s not over. Congress must continue to hold Trump accountable.

Harry Litman: Will acquittal kill the impeachment clause? The voters get the final say.

George Conway: I believe the president, and in the president

The Post’s View: How the Senate can still hold Trump accountable

The latest commentary on the Trump impeachment

Looking for more Trump impeachment coverage following the president’s acquittal?

See Dana Milbank’s Impeachment Diary: Find all the entries in our columnist’s feature.

Get the latest: See complete Opinions coverage from columnists, editorial cartoonists and the Editorial Board.

Read the most recent take from the Editorial Board: It’s not over. Congress must continue to hold Trump accountable.

The House impeachment managers weigh in in an op-ed: Trump won’t be vindicated. The Senate won’t be, either.

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