Sen. Mitt Romney of Utah said Wednesday that he will vote to convict President Donald Trump for abusing his power, making him the only Republican in the Senate to publicly side with Democrats calling for Trump's removal from office.
"I do believe he should be removed from office. That's the vote that I will take in just a short a while," Romney said in a Fox News interview that aired Wednesday.
Romney shared his decision with multiple outlets just a few hours before the Senate is set to hold its final vote to reach a verdict on the two articles of impeachment that passed the House in December. That vote is scheduled for 4 p.m. ET.
Minutes before the vote was scheduled to begin, red-state Democratic Sen. Joe Manchin of West Virginia announced that he will vote for both articles of impeachment. Manchin's decision to vote with his party was not guaranteed; he had recently proposed a resolution to censure Trump in the Senate.
NBC News reported that Romney will vote to convict Trump on the first article of impeachment, which alleges Trump abused his power by pressuring Ukraine's president to announce investigations into his political opponents while he withheld nearly $400 million in congressionally appropriated military aid to Kyiv.
But Romney reportedly said he will vote against the second article, in which Trump allegedly obstructed Congress by refusing to cooperate with the House impeachment inquiry, and pressuring potential witnesses not to comply.
Trump maintains that he has done nothing wrong.
On the Senate floor just two hours before the final vote was set to begin, Romney said, "Voters will make the final decision, just as the president's lawyers have implored. My vote will likely be in the minority in the Senate."
"But," he added, "irrespective of these things, with my vote, I will tell my children and their children that I did my duty."
The announcement marks Romney as not only the sole Republican to vote for Trump's removal, but as the first senator in American history to vote to convict a president from his own party.
Romney, who was the Republican nominee for president against Barack Obama in 2012, has been a fierce critic of Trump's dating back to the 2016 presidential campaign.
Romney was one of just two GOP senators to vote in favor of allowing additional witnesses and documents in the Trump's impeachment trial. The other senator, Susan Collins of Maine, announced Tuesday that she would vote to acquit Trump on both articles.
On the Senate floor Wednesday afternoon, Romney said that "the grave question the Constitution tasks senators to answer is whether the president committed an act so extreme and so egregious" that it warrants impeachment.
Romney concluded: "Yes, he did."
"The president's purpose was personal and political. Accordingly, the president is guilty of an appalling abuse of public trust," Romney said.
"What he did was not perfect. No, it was a flagrant assault on our electoral rights, our national security, and our fundamental values," Romney continued. "Corrupting an election to keep oneself in office is perhaps the most abusive and destructive violation of one's oath of office that I can imagine."
Romney acknowledged that his vote will not change the outcome of the trial, in which Trump is virtually guaranteed to be acquitted. The GOP holds a 53-47 majority in the Senate; It would take 67 votes convict Trump.
But he said that the pressure to side with Trump was nonetheless immense.
"In the last several weeks, I've received numerous calls and texts, many demanding with their words that I stand with the team. I can assure you that thought has been very much on my mind," Romney said.
"I support a great deal of what the president had done. I voted with him 80 percent of the time. But my promise before God to apply impartial justice required that I put my personal feelings and political biases aside."
The reaction from Trump's supporters was swift and severe.
"Mitt Romney's actions today are wildly out of step with his own constituents," the Republican National Committee told NBC in a statement. "President Donald Trump is more popular in Utah than Mitt Romney."
Trump campaign spokesman Tim Murtaugh told CNBC, "The President did nothing wrong and the Republican Party is united behind him."
Trump's son, Donald Trump Jr., claimed in a tweet that Romney is "forever bitter that he will never be" president. "He's now officially a member of the resistance & should be expelled from the @GOP."
GOP chairwoman Ronna McDaniel — who is Romney's niece — also criticized her uncle's decision.
"This is not the first time I have disagreed with Mitt, and I imagine it will not be the last," she tweeted. "I, along with the @GOP, stand with President Trump."
The White House nor the Trump campaign did not immediately respond to CNBC's requests for comment on Romney's announcement and Trump Jr.'s call for the senator's expulsion from the GOP.
Romney had already received a backlash from other Republican Party figures after he voted Friday for new witnesses in the Senate trial.
Matt Schlapp, chairman of the American Conservative Union, tweeted at that time that Romney was "formally NOT invited" to this year's Conservative Political Action Conference.
Read Romney's full remarks as prepared for delivery.
The Constitution is at the foundation of our Republic's success, and we each strive not to lose sight of our promise to defend it. The Constitution established the vehicle of impeachment that has occupied both houses of Congress for these many days. We have labored to faithfully execute our responsibilities to it. We have arrived at different judgments, but I hope we respect each other's good faith.
The allegations made in the articles of impeachment are very serious. As a Senator-juror, I swore an oath, before God, to exercise "impartial justice." I am a profoundly religious person. I take an oath before God as enormously consequential. I knew from the outset that being tasked with judging the President, the leader of my own party, would be the most difficult decision I have ever faced. I was not wrong.
The House Managers presented evidence supporting their case; the White House counsel disputed that case. In addition, the President's team presented three defenses: first, that there can be no impeachment without a statutory crime; second, that the Bidens' conduct justified the President's actions; and third that the judgement of the President's actions should be left to the voters. Let me first address each of those defenses.
The historic meaning of the words "high crimes and misdemeanors," the writings of the Founders and my own reasoned judgement convince me that a president can indeed commit acts against the public trust that are so egregious that while they are not statutory crimes, they would demand removal from office. To maintain that the lack of a codified and comprehensive list of all the outrageous acts that a president might conceivably commit renders Congress powerless to remove a president defies reason.
The President's counsel noted that Vice President Biden appeared to have a conflict of interest when he undertook an effort to remove the Ukrainian Prosecutor General. If he knew of the exorbitant compensation his son was receiving from a company actually under investigation, the Vice President should have recused himself. While ignoring a conflict of interest is not a crime, it is surely very wrong.
With regards to Hunter Biden, taking excessive advantage of his father's name is unsavory but also not a crime. Given that in neither the case of the father nor the son was any evidence presented by the President's counsel that a crime had been committed, the President's insistence that they be investigated by the Ukrainians is hard to explain other than as a political pursuit. There is no question in my mind that were their names not Biden, the President would never have done what he did.
The defense argues that the Senate should leave the impeachment decision to the voters. While that logic is appealing to our democratic instincts, it is inconsistent with the Constitution's requirement that the Senate, not the voters, try the president. Hamilton explained that the Founders' decision to invest senators with this obligation rather than leave it to voters was intended to minimize—to the extent possible—the partisan sentiments of the public.
This verdict is ours to render. The people will judge us for how well and faithfully we fulfilled our duty. The grave question the Constitution tasks senators to answer is whether the President committed an act so extreme and egregious that it rises to the level of a "high crime and misdemeanor."
Yes, he did.
The President asked a foreign government to investigate his political rival.
The President withheld vital military funds from that government to press it to do so.
The President delayed funds for an American ally at war with Russian invaders.
The President's purpose was personal and political.
Accordingly, the President is guilty of an appalling abuse of the public trust.
What he did was not "perfect"— No, it was a flagrant assault on our electoral rights, our national security interests, and our fundamental values. Corrupting an election to keep oneself in office is perhaps the most abusive and destructive violation of one's oath of office that I can imagine.
In the last several weeks, I have received numerous calls and texts. Many demand that, in their words, "I stand with the team." I can assure you that that thought has been very much on my mind. I support a great deal of what the President has done. I have voted with him 80% of the time. But my promise before God to apply impartial justice required that I put my personal feelings and biases aside. Were I to ignore the evidence that has been presented, and disregard what I believe my oath and the Constitution demands of me for the sake of a partisan end, it would, I fear, expose my character to history's rebuke and the censure of my own conscience.
I am aware that there are people in my party and in my state who will strenuously disapprove of my decision, and in some quarters, I will be vehemently denounced. I am sure to hear abuse from the President and his supporters. Does anyone seriously believe I would consent to these consequences other than from an inescapable conviction that my oath before God demanded it of me?
I sought to hear testimony from John Bolton not only because I believed he could add context to the charges, but also because I hoped that what he said might raise reasonable doubt and thus remove from me the awful obligation to vote for impeachment.
Like each member of this deliberative body, I love our country. I believe that our Constitution was inspired by Providence. I am convinced that freedom itself is dependent on the strength and vitality of our national character. As it is with each senator, my vote is an act of conviction. We have come to different conclusions, fellow senators, but I trust we have all followed the dictates of our conscience.
I acknowledge that my verdict will not remove the President from office. The results of this Senate Court will in fact be appealed to a higher court: the judgement of the American people. Voters will make the final decision, just as the President's lawyers have implored. My vote will likely be in the minority in the Senate. But irrespective of these things, with my vote, I will tell my children and their children that I did my duty to the best of my ability, believing that my country expected it of me. I will only be one name among many, no more or less, to future generations of Americans who look at the record of this trial. They will note merely that I was among the senators who determined that what the President did was wrong, grievously wrong.
We're all footnotes at best in the annals of history. But in the most powerful nation on earth, the nation conceived in liberty and justice, that is distinction enough for any citizen.
-- CNBC's Yelena Dzhanova contributed to this report.