Republican Rep. Jason Chaffetz of Utah is planning to run for House speaker in a surprise longshot challenge to House Majority Leader Kevin McCarthy, according to three Republican aides with knowledge of the situation.

Chaffetz chairs the Oversight and Government Reform Committee and has led high-profile hearings on the Secret Service, Planned Parenthood and other issues.

In recent days he's 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, that 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 who confirmed his plans demanded anonymity to discuss them ahead of a public announcement. The news was first reported by Politico.

Chaffetz' plans injects new turmoil into the House GOP just a week after Speaker John Boehner shocked Capitol Hill by announcing he would resign rather than face a tea party-backed floor vote on his speakership.

But Chaffetz' entry into the race would come less than a week before the Oct. 8 elections and with McCarthy 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.

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."