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 run for any office — in 2018.

Mr. Chaffetz, 50, a Utah Republican who 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.”

He said his decision was not based on 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.