WASHINGTON — California Republican Kevin McCarthy quickly amassed support to become House majority leader on Thursday, but his likely ascent shut conservatives out of the chamber’s top leadership jobs, leaving them fuming and exposing fissures within the GOP.

Within 48 hours of Rep. Eric Cantor’s surprising primary-election downfall, McCarthy and his deputies aggressively rounded up votes with a pitch to Southern Republicans and pointed private conversations on the House floor in a race that occasionally had the markings of a personality-driven contest.

Republicans sought to project an aura of unity but failed to quiet conservative complaints that such quick party elections after Cantor’s defeat gave them little time to rally around an alternative who better reflects the right’s ideology and the emboldened tea party.

Votes are scheduled for next Thursday for majority leader, the No. 2 job behind Speaker John Boehner, and for majority whip, the No. 3 party post.

But that may well not be the end of it. Several Republicans asserted that next week’s action won’t quiet ambitious lawmakers or factions in the GOP caucus, and leadership contests after November’s national midterm elections could produce a brand new lineup.

Despite conservative discontent, Boehner’s job does not appear to be in serious jeopardy for now.

But some lawmakers noted there was a limit to his security.

“The speaker is speaker in 24-hour increments. Literally 50 guys can call a revolt,” said Rep. Tom Cole of Oklahoma, a Boehner ally.

Cantor suffered a stunning defeat to little-known college professor Dave Brat in Tuesday’s Virginia Republican primary, a race that underscored the divide within the GOP between pragmatic, establishment conservatives and farther-right contenders pressing for no-compromise ideological stances.

Brat cast Cantor’s past positive comments on possible immigration changes as amnesty for those here illegally – a characterization Cantor heatedly rejected – and turned it into a defining issue in the race.

Cantor is the first House majority leader to lose his seat by being defeated in a party primary election since the post was created in 1899, according to Eric Ostermeier, research associate at the University of Minnesota’s Center for the Study of Politics and Governance.

Cantor announced on Wednesday that he would step down as majority leader at the end of July. He endorsed McCarthy as his successor and the House whip moved swiftly to secure the votes.

“I don’t think anyone counts votes better around here, and I think he has a very, very commanding lead,” said Rep. Cole.

McCarthy, the four-term congressman from Bakersfield, California, will face Texas Rep. Pete Sessions, the chairman of the Rules Committee, in the contest for majority leader.

Another Texan with stronger bona fides in the conservative ranks, Rep. Jeb Hensarling, declined to enter the race on Thursday.

If conservatives were powerless to put the brakes on McCarthy’s quick rise they weren’t keeping quiet about their frustration.

Rep. Steve King, R-Iowa, was among several lawmakers calling on GOP leaders to put off the election, suggesting it was rigged.

“Leadership’s tactic has always been call the election as fast as you can, don’t let anybody have time to organize except those who had the heads-up and the head start,” King said.

Hensarling had been the conservatives’ choice, and King and others had no one else to get behind.

“I’m looking for a candidate that has not supported some form of amnesty, and Jeb fit that, and now we don’t have an announced candidate that fits that and I’m very troubled by that,” King said.