Senator Mitt Romney of Utah, the 2012 Republican nominee for president who made a historic break with his party when he voted to remove former President Donald J. Trump from office, announced on Wednesday that he would not seek re-election in 2024, saying he wanted to make way for a “new generation of leaders.”
He strongly suggested that Mr. Trump, 77, and President Biden, 80, should follow his lead and bow out to pave the way for younger candidates, arguing that neither was effectively leading his party to confront the “critical challenges” the nation faces.
“At the end of another term, I’d be in my mid-80s. Frankly, it’s time for a new generation of leaders,” Mr. Romney, 76, said in a video statement. “They’re the ones that need to make the decisions that will shape the world they will be living in.”
The announcement was in some ways the culmination of a long divergence between Mr. Romney, a genteel and wealthy former governor and traditional conservative, and the Republican Party, which has shifted under his feet and embraced a coarser brand of partisanship in recent years.
“There’s no question that the Republican Party today is in the shadow of Donald Trump,” Mr. Romney said on Wednesday, noting that the far right of the G.O.P. is less concerned with policy and more focused on “resentment and settling scores and revisiting the 2020 election.”
Elected to the Senate in 2018, Mr. Romney has struggled to find his place within a party that has veered sharply to the right and in a Capitol where a majority of Republicans remain loyal to Mr. Trump — at least publicly. His decision to step down, which he had been weighing for months, came just weeks before the release of a biography of him, “Romney: A Reckoning,” in which Mr. Romney reveals that many of his Republican colleagues privately ridicule and disdain Mr. Trump.
At one point, Mr. Romney recounts how Senator Mitch McConnell of Kentucky, the minority leader, called him “lucky,” saying that he was able to “say the things that we all think.”
“You’re in a position to say things about him that we all agree with but can’t say,” Mr. McConnell told Mr. Romney, according to an excerpt from the book published in The Atlantic on Wednesday. Mr. Romney said that “more than a dozen” Republican senators had made similar comments to him expressing envy at his ability to criticize Mr. Trump publicly.
In the upcoming book, written by McKay Coppins, Mr. Romney also recalled a 2019 visit by Mr. Trump to the weekly Senate Republican lunch in the Capitol. The senators were attentive and encouraging during the president’s remarks about what he called the “Russia hoax” and how they would soon be known as “the party of health care,” but burst into laughter after Mr. Trump left the room, according to the excerpt.
The book also delves into Mr. Romney’s dissatisfaction with the Senate, a place he described as an “old men’s club,” full of performative politics and people obsessed with their own re-election. In the Senate, Mr. Romney has joined an array of bipartisan “gangs” seeking to take on major policy issues — including infrastructure, gun safety and overhauling the Electoral Count Act — but rarely sought to lead those efforts.
In the video announcing his retirement, Mr. Romney said that neither Mr. Biden nor Mr. Trump, the current front-runner for the Republican nomination, was addressing the nation’s most critical challenges, including climate change, mounting debt and authoritarian threats from Russia and China, and hinted that they were not fit to lead the nation into the future.
“It would be a great thing if both President Biden and former President Trump would stand aside,” Mr. Romney told reporters later on Capitol Hill.
His call came amid renewed scrutiny of the age of Mr. Biden and other prominent elected officials including Mr. McConnell, 81, the minority leader whose recent health issues have raised questions about whether he is fit to continue in his post.
But Mr. Romney rejected the suggestion that Mr. McConnell should step aside.
“He’s in a position to make a real difference at his age,” Mr. Romney said. “If I were majority leader of the Senate, I might reach a different decision, too. But I’m not.”
Mr. Romney also said he received a call from Mr. Biden after his announcement, which he described as “very generous, and very kind.”
Mr. Romney, who sought the presidency twice and describes his career in politics as a moral mission driven by his Mormon faith, hinted that he might still have some role to play in the nation’s political discourse, saying, “I’m not retiring from the fight.” He said he planned to finish out his term, which ends in January 2025.
Utah is a solidly Republican state, so Mr. Romney’s departure is highly unlikely to affect the balance of power on Capitol Hill. He had recently told people that he planned to make a decision about seeking re-election by the end of the year and that he was weighing whether he could still play any productive role in Congress. Mr. Romney was also cognizant that he would face a tough primary fight if he decided to run again.
His decision to abandon a career in the Senate followed similar decisions from many moderate House Republicans last year. In the 2022 midterm elections, four House Republicans who voted to impeach Mr. Trump declined to run for re-election.
Mr. Romney said on Wednesday that he was proud of his record working on gun safety legislation and the Electoral Count Act, but that “looking forward, I think it’s going to be more challenging for something like that to occur again.”
Mr. Romney had also begun to stir speculation that he was ready to move on from the Senate when he agreed to participate in Mr. Coppins’s biography, which is set to be published next month by Scribner. In the book, Mr. Romney is said to quote many of his colleagues by name in discussing how Republican lawmakers really view and talk about Mr. Trump in private when the former president is not present.
Mr. Coppins is said to have conducted hours of interviews with Mr. Romney for the book and was given access to the senator’s emails and diary. The book’s impending release already has his colleagues concerned about their private thoughts and conversations regarding the party’s vengeful presidential front-runner being aired publicly.
Mr. Romney has also appeared increasingly concerned about the likelihood that Mr. Trump would emerge as his party’s nominee.
In a recent opinion piece in The Wall Street Journal, Mr. Romney implored donors and Republican candidates to unite around an alternative to Mr. Trump, for fear of delivering him the party’s nomination. “Donors who are backing someone with a slim chance of winning,” he wrote, “should seek a commitment from the candidate to drop out and endorse the person with the best chance of defeating Mr. Trump by Feb. 26.”