WASHINGTON (AP) — Republican Rep. Jason Chaffetz of Utah plans to run for House speaker in a surprise longshot challenge to House Majority Leader Kevin McCarthy, three Republican aides said Friday, injecting new turmoil into an unsettled House Republican conference.

Chaffetz chairs the Oversight and Government Reform Committee and has led high-profile hearings on the Secret Service, Planned Parenthood and other issues. His candidacy would offer an outlet for Republicans reluctant to coronate McCarthy to replace House Speaker John Boehner, who shocked Capitol Hill a week ago by announcing his resignation under conservative pressure.

Yet it’s not clear the hardliners who ousted Boehner and view McCarthy with suspicion would flock to Chaffetz instead.

In recent days Chaffetz has been highly critical of McCarthy over comments the majority leader made suggesting political motives for the House committee investigating the 2012 attacks on U.S. diplomatic facilities in Benghazi, Libya. The attacks killed four Americans, including Ambassador Chris Stevens.

Chaffetz’ office did not respond to multiple requests for comment, but Chaffetz plans to appear on Fox News Sunday to “announce his decision to run for House speaker,” according to that network.

The aides with knowledge of his plans demanded anonymity to confirm them ahead of a public announcement. The news was first reported by Politico.

Chaffetz’ entry into the race would come less than a week before the Oct. 8 leadership elections, giving him little time to build support. McCarthy is seen as the commanding favorite, despite Republicans’ discomfort over the Californian’s boast this week that the Benghazi committee could take credit for Hillary Rodham Clinton’s lagging poll numbers. Clinton is the front-runner for the Democratic presidential nomination and was secretary of state at the time of the Benghazi attacks.

McCarthy subsequently said he regretted the comment and did not mean to imply the committee is political because it is not. But Democrats pounced and said the remarks revealed the Benghazi committee is a political witch hunt.

In an appearance Friday on conservative host Sean Hannity’s radio show, Chaffetz pledged a strong fight for conservative goals.

“Speaker Boehner, bless his heart, has done some good stuff — he got rid of earmarks. But I’m tired of not actually getting to the end zone. I want to actually change the trajectory, I don’t want to say we coulda, woulda, shoulda. I want to score touchdowns.”

Chaffetz, 48, and in his fourth term, arrived in Congress with hardline conservative backing, but as a committee chairman is now seen by some as an ally of leadership. He angered some conservatives by briefly revoking Rep. Mark Meadows’ subcommittee chairmanship when Meadows and others Republicans defied party leaders in a vote on a trade bill, and some are still smarting.

“It would be hard to replace John Boehner with someone who also kicks people off committees for their votes,” sniped Rep. Thomas Massie, R-Ky., who is backing another candidate, Rep. Daniel Webster, R-Fla.

Earlier this week Chaffetz said McCarthy should apologize for “a total mischaracterization” of the work of the Benghazi committee, but at the time Chaffetz said he still supposed McCarthy’s bid for speaker.

And Chaffetz also tried earlier this week to push his friend Rep. Trey Gowdy, R-S.C., who chairs the Benghazi committee, to run for majority leader, but Gowdy declined.

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Associated Press writers Mary Clare Jalonick and Matthew Daly contributed to this report.

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