WASHINGTON — House Republican turmoil is boiling over as leadership elections approach, with dissatisfied lawmakers casting about for new choices and a surprise longshot challenger emerging in the speaker’s race.

The upheaval reflects a caucus ever more divided in the week since House Speaker John Boehner stunned Capitol Hill by resigning under conservative pressure. And it comes as a long list of weighty and polarizing issues loom on Congress’ agenda, including raising the federal borrowing limit to avoid a market-shattering default, and paying the bills to keep the government running.

Rep. Jason Chaffetz of Utah, the brash 48-year-old chairman of the high-profile House oversight committee, intends to challenge the prohibitive favorite for speaker, Majority Leader Kevin McCarthy of California, Republican aides said Friday. Yet it’s not clear that the hardliners who ousted Boehner and view McCarthy with suspicion would flock to Chaffetz, given that as committee chairman he’s enforced leadership initiatives such as punishing lawmakers who buck the party position.

“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.

That raises the prospect of more unrest — and potentially even more candidates — before votes for the new leadership team are cast Oct. 8.