Facing new district lines and a tough primary race, Representative Fred Upton of Michigan, announced his retirement on Tuesday, becoming the fourth House Republican who voted to impeach former President Donald J. Trump to decline to run for re-election.
Mr. Upton, who has served in Congress for more than three decades, had his Western Michigan district significantly redrawn in the once-a-decade reapportionment process, and he was facing a difficult primary campaign against Representative Bill Huizenga, whom Mr. Trump endorsed last month.
“This is it for me,” Mr. Upton said in an emotional departure speech on the House floor, lamenting the divisiveness of politics today. “Hopefully civility and bipartisanship versus discord can rule and not rue the day.”
Of the 10 House Republicans to vote for Mr. Trump’s impeachment last year, the others who have chosen retirement are Representatives Adam Kinzinger of Illinois, Anthony Gonzalez of Ohio and John Katko of New York.
Mr. Upton’s district, which includes Kalamazoo, was divided in the redistricting process, taking in more territory near Grand Rapids, which Mr. Huizenga, who has been in Congress since 2011, currently represents.
Mr. Trump celebrated the latest retirement in a statement: “UPTON QUITS! 4 down and 6 to go. Others losing badly, who’s next?”
Mr. Upton has been an institutionalist in the House, returning even after his term as chairman of the powerful Energy and Commerce Committee had been completed and his party was in the minority.
“Fred Upton is a legislator first and foremost,” said Doug Heye, a former aide to House Republican leadership, saying Mr. Upton’s work on opioid addiction and the 21st Century Cures Act, a sweeping health care law passed in 2016, “should be the model” for bipartisan accomplishments.
As recently as Monday, Mr. Upton was speaking like a potential candidate, telling NBC News that if he won in 2022, it would show that Mr. Trump was “not as strong as he might have thought that he was.”
Yet in the same interview, Mr. Upton showed some doubts about his plans. “I’m going to run my own race — if we run — we’re going to run our own race,” he said.
In retiring, Mr. Upton invoked his early service in the Reagan administration, where he worked in the Office of Management and Budget. “Reagan worked both sides of the aisle to get things done, caring less about who got the credit,” Mr. Upton said in his speech. “And I made a promise that such a principle would be my guiding light.”
He was followed immediately on the floor by a Democrat, Representative Debbie Dingell of Michigan, who called his retirement a “loss for this country.”
“Fred and I always managed to disagree without vitriolic rhetoric,” she said, calling him a “best friend” to her late husband, former Representative John D. Dingell Jr., who died in 2019.
Annie Karni contributed reporting from Washington.