“What he did was not perfect. No, it was a flagrant assault on our electoral rights, our national security, and our fundamental values,” he said.
All 52 other Republicans have signaled they will vote to acquit the president, saying that the House didn’t prove its case, that the accusations against the president don’t rise to the level of impeachable crimes, and saying the president had a reason to want former Vice President Joseph R. Biden, a political rival, to be investigated.
Mr. Romney rejected each of those.
He acknowledged his vote won’t change the outcome — the president will be acquitted, and it won’t even be close. It would take 67 votes to convict him.
Mr. Romney has had a rocky relationship with Mr. Trump and with the GOP. He was the party’s presidential nominee in 2012, losing in what election analysts said should have been winnable against President Obama.
In 2016 he vehemently opposed Mr. Trump, who then revealed that Mr. Romney was “begging” for an endorsement in the previous election.
Mr. Trump buried the hatchet in 2018, endorsing Mr. Romney for the Senate seat he now holds.
No senator has ever voted to convict a president of his own party.
All 12 Democrats voted to acquit President Andrew Johnson in 1868, and all Democrats voted to acquit President Clinton in 1999.
House Democrats voted by party-line to impeach Mr. Trump on Dec. 18 on two articles.
The first accuses him of abuse of power stemming from a July phone call with the Ukrainian president where Mr. Trump requested a corruption probe into a political rival, former Vice President Joseph R. Biden, and Democrats’ activities in 2016, while withholding financial aid to Ukraine.
A second article accuses the president of obstruction of Congress for claiming immunity from the House’s probe and blocking witnesses and documents Democrats sought.
No Republicans voted for the articles in the House, marking the first time the impeachment of a president happened on a purely partisan basis. A few House Democrats actually broke with House Speaker Nancy Pelosi, voting against impeachment.
“He was going to go his own way,” said Sen. John Thune, South Dakota Republican, reflecting on Mr. Romney’s announcement.
“Everybody has to do what they think is the right thing,” he added.
Mr. Thune, the second-ranking Republican, noted his conference will continue to work with Mr. Romney.
“I don’t think it changes very much,” he added. “He and the president had a little bit of a complicated relationship to start with.”