WASHINGTON — Representative Jason Chaffetz, the powerful chairman of the House Oversight Committee, told supporters on Wednesday that he would not seek re-election to Congress — or for any office — in 2018.
Mr. Chaffetz, 50, a Utah Republican who plainly relished his oversight role more under a Democratic administration, said he was ready to return to the private sector after more than 13 years in public service, calling his decision a “personal” one.
“I have long advocated public service should be for a limited time and not a lifetime or full career,” he said in a statement posted on Facebook. “After more than 1,500 nights away from my home, it is time.”
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He said his decision was not based on either health or political concerns, adding that he was “confident” of his re-election should he have pursued it and retained support from Speaker Paul D. Ryan for his committee chairmanship.
More than 18 months out from the election in the heavily Republican district, there were already possible signs of a challenging race in Mr. Chaffetz’s future. Kathryn Allen, a physician and political newcomer running as a Democrat, has already raised nearly $400,000 more than Mr. Chaffetz this year, The Salt Lake Tribune reported Sunday — most of it from donors outside of Utah. And Mr. Chaffetz had also acquired a primary challenger: Damian W. Kidd, a lawyer and another newcomer who accused the congressman of caring more about himself than his district.
Last year, Mr. Chaffetz publicly weighed the possibility of running for governor of Utah in 2020, when his committee chairmanship would be set to expire.
Even with his announcement, Mr. Chaffetz left open the possibility of his return.
“I may run again for public office,” he added, “but not in 2018.”
Mr. Ryan on Wednesday praised Mr. Chaffetz as “a great defender of liberty and limited government.”
On Capitol Hill, Mr. Chaffetz has shown an opportunistic streak, often rushing toward television cameras with an eager smile. During the election, he vacillated several times before backing President Trump. He said he would not be able to look his teenage daughter in the eye should he vote for Mr. Trump after revelations arose that Mr. Trump had boasted in 2005 of sexually assaulting women. Then he voted for him. And he vowed to investigate Hillary Clinton whether she won or not.
With a ready foil in Mrs. Clinton, whose brushes with controversy have sustained many Republican congressional careers, Mr. Chaffetz appeared primed to emerge as a chief tormentor for a new Democratic White House.
Instead, as much as perhaps any member of Congress, his fortunes turned considerably with Mr. Trump’s victory.
During his time heading the committee, Mr. Chaffetz has focused often on two pet issues: criticizing the Secret Service for security lapses and holding Mrs. Clinton to account.
After the F.B.I. director, James B. Comey, announced in July that the bureau would recommend that Mrs. Clinton not be charged over her use of a private email account when she was secretary of state, Mr. Chaffetz led House Republicans in rejecting Mr. Comey’s conclusion.
Five days after the announcement, Mr. Chaffetz asked the Justice Department to investigate whether Mrs. Clinton had lied in her testimony before Congress about the 2012 attacks in Benghazi, Libya. Mr. Chaffetz had been one of the first lawmakers to raise questions about the Obama administration’s role in Benghazi, traveling to Libya less than a month after the attacks to evaluate security standards.
“It’s the nature of being the committee chairman to conduct oversight of the administration,” he said last year, describing his role as a pursuit of facts, not a political agenda.
But with Mr. Trump’s surprise victory in November, Mr. Chaffetz found himself in an uncomfortable position: a watchdog who often sounded disinclined to watch over a fellow Republican.
When Mr. Trump’s former national security adviser, Michael T. Flynn, resigned in February amid reports of his contacts with the Russian ambassador, Mr. Chaffetz appeared eager to move on.
“I think that situation has taken care of itself,” he said.
Other controversies had nothing to do with oversight.
Last month, as his party bickered over how to replace President Barack Obama’s signature health care law, Mr. Chaffetz came under fire for suggesting that uninsured Americans should spend money on their own health care “rather than getting that new iPhone that they just love.”
Opposition to Mr. Chaffetz has met him at his adopted doorstep as well. His tightfisted control of the District of Columbia’s laws, which fall under his committee’s purview, has been rewarded with a D.C.-born, anti-Chaffetz political action committee.
First elected in 2008, Mr. Chaffetz, who was once a kicker on the Brigham Young University football team, has taken pride in sleeping in his office to save money.
Seizing on the turmoil that followed the resignation of John A. Boehner as House speaker, Mr. Chaffetz emerged as a contender after support began to erode for Representative Kevin McCarthy of California, the Republican majority leader who had been expected to inherit the gavel. But he stepped aside when it became clear that Mr. Ryan would gather enough support.
Besides, being speaker at such a volatile time in Congress is “not good for career longevity,” Mr. Chaffetz told The New York Times in 2015. “But I don’t plan to be here that long.”