The five-term Republican, who rose from a relatively unknown figure to the chairmanship of one of Congress' most powerful committees, said he would return to the private sector after his term ends in January 2019 and that his decision is based solely on his promise to serve a short time and his yearning to spend more time with his family.
"I love the work, but I love my family more. People will try to come up with guesses and none of which will be true of why I'm leaving," he said, adding that he may later opt for another bid for office, including Utah governor. Gov. Gary Herbert has said he's not likely to seek another term.
"All the options are still on the table," Chaffetz said. "I'm not opening or closing the door on anything."
As chairman of the House Oversight and Government Reform Committee, Chaffetz has faced increasing criticism for his lack of investigation into President Donald Trump's potential conflicts of interest and Russia's meddling in the U.S. election. He was jeered at a recent town hall. And an unknown Democrat, Kathryn Allen, had amassed $500,000 $100,000 more than Chaffetz to challenge him.
But Chaffetz said these factors played no role in his decision.
"For those that would speculate otherwise, let me be clear that I have no ulterior motives," he wrote on Facebook early Wednesday. "I am healthy. I am confident I would continue to be re-elected by large margins."
While Chaffetz played coy on his future plans, the website jasonforgovernor.com redirects to his campaign website for the House.
Herbert said he "was as stunned as anyone" to hear that Chaffetz would not seek re-election.
"His razor-sharp mind, expansive knowledge and gift for communicating will serve him well when he transitions into the private sector," Herbert said.
House Speaker Paul Ryan, R-Wis., who Chaffetz said had pleaded with him to run again for his seat, praised the Utah congressman in a tweet, calling him a "great defender of liberty and limited government." White House Chief of Staff Reince Priebus texted Chaffetz that he was "Shocked!" and then called to chat.
Sen. Orrin Hatch, R-Utah, lauded Chaffetz's track record as Oversight chairman.
"His work on that committee has been really very fruitful and very good," Hatch said. "He's got guts, he's an attractive personality. I think Utah should be proud of him."
Hatch accepted at face value Chaffetz's statement that he wanted to spend more time with family.
"He's kind of tired of being back there all the time. I understand that syndrome," said the seven-term senator who recently said he plans to run again next year.
Democrats, meanwhile, were ecstatic that Chaffetz would head for the sideline.
"He's setting a good example for the rest of our delegation who need to remember that public service is not a lifetime venture," said Utah Democratic Party Chairman Peter Corroon.
The Democratic Congressional Campaign Committee pounced on Chaffetz's decision, saying his "behavior has long been beneath the dignity of the office he holds," and he should step down immediately from his Oversight Committee perch.
"Clearly, Chaffetz crumbled under the weight of the widespread backlash that he's been facing for refusing to do his job, which is a victory for all Americans and will serve as a motivating force for the grass roots," said DCCC spokesman Tyler Law.
Chaffetz said there was no chance that his district which is heavily Republican would end up electing a Democrat.
"This is Utah, not fantasy land," he quipped.
The former Brigham Young University football kicker and business executive ran Jon Huntsman's winning gubernatorial campaign in 2004 and served as his first chief of staff. He later successfully challenged six-term Republican Rep. Chris Cannon in 2008. Cannon, who has virtually disappeared from politics, declined to comment Wednesday.
Chaffetz, known as a media-savvy politician who makes frequent appearances on Fox News and often takes his own press calls, made a brief run for House speaker after John Boehner, R-Ohio, stepped down.
National Republican Congressional Committee Chairman Steve Stivers said Chaffetz was a "valuable member" of the GOP caucus and "we wish him the best as he begins this new chapter in his life."
Stivers added that the NRCC was confident the seat would remain in the GOP column.
"Republicans have a deep bench of talented candidates in Utah who are more than up to this challenge," Stivers said in a statement.
Rep. Chris Stewart, R-Utah, said he was "saddened" to learn Chaffetz won't seek re-election.
"He is a good friend, terrific public servant and a colleague that will be greatly missed in the House of Representatives and in the Utah delegation," Stewart said. "I wish him all the best in his future endeavors."
Rep. Mia Love also commended Chaffetz for his time in office, noting that he "served with distinction" and "has become a good friend."
"Utah's entire delegation has worked well together and his contribution will be missed," she added. "I am sure he will continue to serve the rest of this term with the same dedication, commitment and energy he has given the previous eight years."
Eight-term Republican Rep. Rob Bishop saluted Chaffetz and said he won't be "letting him off the hook" during his remaining two years.
"I understand his decision, for I have set my own timeline," he said. "There will always be one more battle to fight and one more issue to resolve, so I truly respect his decision to do what is best for his family."
Praise came from across the aisle as well.
Rep. Elijah Cummings of Maryland, the top Democrat on the Oversight Committee who has sparred with Chaffetz on occasion, said the Utahn was "tenacious and dedicated."
"He has fundamentally changed the culture on our committee so members, as he says, can disagree without being disagreeable," Cummings said, noting that he had visited Utah with Chaffetz a few years ago. "After seeing his district and his state firsthand, I can certainly understand why it is calling him back."
The previous Oversight chairman, Rep. Darrell Issa, R-Calif., was criticized for ignoring the Democratic minority in relentlessly pressing his partisan agenda.
Chaffetz's decision to step down was welcomed in Washington, at least by the residents who have been angry that the Utah conservative was attempting to overturn progressive legislation passed by the District of Columbia. D.C. residents have no voting member of Congress, which has broad authority over the federal city.
"This is great news for everyone in D.C.," said City Councilman Charles Allen, "who was frustrated with Rep. Jason Chaffetz's attempts to block and change local D.C. laws from his perch in Congress."
Reporters Courtney Tanner and Jennifer Dobner contributed to this report.