On May 16, Chaffetz announced the Oversight committee wanted to see a memo prepared by Comey about interactions with Trump, and tweeted that he had "his subpoena pen ready" to obtain it.
Since Trump's election, Chaffetz has faced increasing pressure from constituents to more aggressively scrutinize President Trump's business dealings and his campaign's alleged ties to Russian Federation. Mr. Chaffetz won 73% of the vote in the 2016 election and Utah's entire congressional delegation is Republican. As the Salt Lake Tribune reported, Gov. Gary Herbert wants an expedited special election, in which voters determine both the party primaries and the general.
Chaffetz had previously said he would leave Congress before the end of his term, but did not provide a timeline.
With several investigations still ongoing, Chaffetz said he was not anxious about other Republican members of the committee continuing his work.
Asked Thursday whether he had any regrets about his time in Congress, Chaffetz said he would like to have completed more investigations.
Chaffetz is the second House Republican who is stepping away from a Trump investigation.
South Carolina Representative Trey Gowdy is considered the favorite to replace Chaffetz after he steps down this summer.
Other Republicans have also faced heat from constituents, but Chaffetz's prominent role and frequent media appearances have made him a lightning rod for critics who say he has not pursued oversight of the Trump administration with the same fervor he did President Barack Obama's. He said he hoped to preside over one final hearing on a botched Obama administration "gun-walking" program, in which federal authorities let gun-runners purchase firearms in hopes of disrupting gun smuggling rings.
It is unclear who would succeed Mr. Chaffetz as chair of the House committee.
"Serving you in the U.S. House of Representatives for almost nine years has been a rare honor and privilege", he said in the statement.
Chaffetz made no official plans for his future, but he has not ruled out running for governor of Utah in 2020.
He says he and his wife will be empty nesters soon and it seems like time to turn a page. "And a lot of people will never ever believe that, but that is the truth".
In February, Washingtonians rallied against Chaffetz for what D.C. Councilmember Charles Allen called his attempt to "override the will of District residents".