The longest-serving Senate Republican announced Tuesday that he will retire at the end of this term, closing out one of the most impressive legislative careers in modern congressional times — and opening the door for a Trump critic to win the seat.
Sen. Orrin G. Hatch released a YouTube video saying 42 years in the Senate — more than any other Republican in history — is long enough, and he won’t seek re-election in November.
“Every good fighter knows when to hang up the gloves, and for me that time is soon approaching,” Mr. Hatch said.
Among those likely to give the race a look is Mitt Romney, the 2012 Republican presidential nominee who made his reputation by running the Winter Olympics in Salt Lake City in 2002 before serving a term as governor of Massachusetts.
But with a Republican-dominated state government and congressional delegation, Utah has other potential candidates as well.
Mr. Hatch, as the senior member of the majority party, serves as president pro tempore of the Senate, putting him third in the line of presidential succession behind the vice president and House speaker.
He has served as chairman of the Senate Judiciary Committee and the Health Education, Labor and Pensions Committee. He is currently chairman of the Finance Committee, where he wrote the Senate version of the tax overhaul that became law late last month.
He also has been involved with creating the Americans with Disabilities Act, the Religious Freedom Restoration Act and the Children’s Health Insurance Program, an add-on to Medicaid that offers government-backed coverage for children whose parents are too wealthy to qualify for Medicaid but too poor to afford coverage on their own.
“From national security to religious freedom, from protecting those with disabilities to accomplishing last year’s historic tax reform, Orrin has led on countless issues of critical importance to the American people,” said Senate Majority Leader Mitch McConnell, Kentucky Republican.
Mr. Hatch said he was particularly proud of having played a role in the confirmation of every member of the Supreme Court dating back 40 years, including all nine current justices.
President Trump was “very sad” to learn of Mr. Hatch’s departure from Capitol Hill, said spokeswoman Sarah Huckabee Sanders.
The president had been urging Mr. Hatch to run for re-election, lobbying him on a flight aboard Air Force One to Utah last month. Mr. Trump and allies such as former strategist Steve Bannon were hoping to avert a Senate bid by Mr. Romney, who has been critical of the president.
Mrs. Sanders said it was too early to talk about Mr. Trump’s involvement in the race to succeed Mr. Hatch.
Mr. Romney didn’t give any hint of his plans. He released a short statement on Facebook saying he considered Mr. Hatch a friend and wishing him well.
Romney backers and Trump critics were already pressing the issue, though.
“In this seat, we must have a leader prepared to meet the challenges of our day and our future. I hope that leader will be @MittRomney,” Evan McMullin said on Twitter.
Mr. McMullin is a Utah Republican who mounted a renegade independent bid for the White House in 2016, hoping to siphon votes from Mr. Trump. His best showing was in Utah, where he won 21 percent — close to Democratic nominee Hillary Clinton’s 27 percent but less than half of Mr. Trump’s 45 percent.
Mr. Hatch is the latest in a string of high-profile Republican retirements, including several Trump critics who chose to depart the Senate rather than run again, and a slew of committee chairmen in the House.
Rep. Bill Shuster, Pennsylvania Republican and chairman of the House Transportation Committee, told The Washington Examiner on Tuesday that he would retire at the end of this year. He joins House Judiciary Committee Chairman Bob Goodlatte of Virginia; House Science, Space and Technology Committee Chairman Lamar Smith of Texas; and House Financial Services Committee Chairman Jeb Hensarling of Texas in heading for the exits.
All four are entering their sixth year as chairmen of their committees and under Republican rules would have to give up their gavels in the next Congress.
Mr. Hatch would have had two more years as the top Republican on the Finance Committee, but his retirement will cut that short.
At a Republican celebration of the tax cut legislation at the White House last month, Mr. Hatch and Mr. Trump showered praise on each other.
“He was just always in there, always fighting for all of us, and did a fantastic job as chairman,” Mr. Trump said.
Mr. Hatch became emotional and nostalgic as he addressed the crowd, including dozens of his colleagues, on the South Lawn. He called Mr. Trump “one heck of a leader.”
“I just hope that we all get behind him every way we can, and we’ll get this country turned around in ways that will benefit the whole world, but, above all, benefit our people and bring us all to a realization of how really great America really is and how the rest of the world depends on us,” Mr. Hatch said.
“I love this country,” Mr. Hatch said. “I came from very humble roots. And I have to say that this is one of the great privileges of my life to stand here on the White House lawn with the president of the United States, who I love and appreciate so much, and with these wonderful colleagues and Cabinet members.”
Colleagues on both sides of the aisle praised Mr. Hatch as the epitome of an old-school gentleman, able to maintain a conservative voting record while working in a bipartisan manner.
His work alongside Sen. Edward M. Kennedy, Massachusetts Democrat, was frequently cited by colleagues who sought to prove the Senate could be friendly and collegial despite deep partisan differences.
“If the two of us — positioned as we were on opposite sides of the political spectrum — could find common ground, we had little trouble enlisting bipartisan support to pass critical legislation that benefited millions of Americans,” Mr. Hatch said in a Newsweek piece after the 2009 death of Kennedy.
Mr. Hatch is also a singer and songwriter, and his office used to give CDs of his music to reporters. He co-wrote “Unspoken,” recorded by Jaci Velasquez, which spent months on Billboard’s top 20 Christian singles chart in 2004 and went platinum.
⦁ Dave Boyer contributed to this report.