Republican Rep. Ken Buck, who had already announced he would not be seeking reelection, announced Tuesday he will leave Congress at the end of next week.
"It has been an honor to serve the people of Colorado's 4th District in Congress for the past 9 years," Buck said in a statement. "I want to thank them for their support and encouragement through the years."
Buck's departure will narrow House Speaker Mike Johnson's already razor-thin majority. With him gone, Republicans will only be able to lose two members of the conference if there is a party-line vote on legislation.
MORE: Retiring Republican congressman slams GOP leaders for 'lying to America'"I look forward to staying involved in our political process, as well as spending more time in Colorado and with my family," Buck said in his statement. He did not elaborate further on why he will not serve out the rest of his term.
Buck, often taking conservative hard-line positions, but also distancing himself from Donald Trump, was one of eight Republicans to vote to oust former Speaker Kevin McCarthy, saying he did so over how McCarthy handled spending issues.
McCarthy also resigned from Congress early, leaving Capitol Hill at the end of last year. Buck supported Johnson to become McCarthy's successor.
He broke with his party on a handful of topics, including their false narratives about the 2020 election and the Jan. 6, 2021 attack on the U.S. Capitol.
In a video last November announcing his decision not to run for sixth term, Buck was highly critical of his his party has handled those two issues.
"These insidious narratives breed widespread cynicism and erode Americans' confidence in the rule of law," he said. "It is impossible for the Republican Party to confront our problems and offer a course correction for the future while being obsessively fixated on retribution and vengeance for contrived injustices of the past.”
He has also cast doubt on the House impeachment inquiry into President Joe Biden and voted against the House impeachment of Homeland Security Secretary Alejandro Mayorkas.
Buck's announcement comes amid a wave of House retirements. Other high-profile GOP exits at the end of this Congress will include Appropriations Committee Chairwoman Kay Granger, China Select Committee Chairman Mike Gallagher and Energy and Commerce Chair Cathy McMorris Rodgers.