– Kevin McCarthy quickly and methodically climbed the power ladder from chief deputy whip, to whip to majority leader of the U.S. House.

Whether the five-term California Republican reaches the top rung largely depends on colleagues in the fractious GOP caucus who on Thursday will pick their nominee to replace resigning Speaker John Boehner of Ohio.

McCarthy’s misstep in a TV interview might give an edge to the brasher and less experienced Jason Chaffetz of Utah, who says he can unify the GOP conference and deliver the GOP message more forcefully.

The full House vote had been scheduled for Thursday, but Boehner changed his mind saying that after talking with colleagues he will postpone that until Oct. 29, his last day as speaker.

Boehner’s resignation comes at a time when his caucus is increasingly fractured, with some of the most conservative members planning the first ouster of a sitting speaker in more than a century. Tea Party members were concerned the speaker wasn’t fighting hard enough for their interests.

Conservatives want a more forceful voice to represent them, but they may not find that in McCarthy, a moderate with a similar leadership style to Boehner’s. And his viability as a speaker nominee became even more tenuous last week after he implied that a special investigation into the 2012 attacks in Libya is politically motivated.

“Everybody thought Hillary Clinton was unbeatable, right? But we put together a Benghazi special committee, a select committee. What are her numbers today? Her numbers are dropping. Why? Because she’s untrustable. But no one would have known any of that had happened had we not fought and made that happen,” McCarthy told Fox News.

The comments drew blowback from both sides, of the aisle, including from Chaffetz, who told MSNBC that it was a “terrible mistake” for McCarthy to characterize the investigation that way. “He was wrong,” said Chaffetz. “We need a speaker who speaks and actually articulates our message.”

Political scientists say McCarthy created a problem for himself at a time when he can least afford it.

“Lives were lost in Benghazi, and this is one of the longest running investigations in congressional history. This is a serious thing that he’s made into a political thing,” said David O’Connell, professor of political science at Dickinson College in Carlisle, Pa.

“McCarthy has really wounded himself, and people will look at him and see those liabilities,” he said.

The delay in the vote could give McCarthy enough time to shore up support after his Benghazi gaffe, but even if he survives the conference vote he could face trouble on the floor. He needs 127 votes from the 246 Republicans in the conference, but on the floor he needs 218. The same conservatives who pushed Boehner out could stand in McCarthy’s way.

“A lot of people think he’s already too closely aligned with Boehner,” O’Connell said.