Republicans are voting for their replacement for John Boehner today - but it's only the start of the mayhem

House Republicans on Thursday are set to vote on their nominee to replace John Boehner as the next House speaker.

But early jockeying for the position has produced even more division in a fractured GOP caucus - and it could signal even more turmoil ahead of a busy calendar filled with deadlines and cliffs over the next few weeks.

Despite a tumultuous past week-plus, House Majority Leader Kevin McCarthy (R-California) is likely to earn the Republican nomination for speaker on Thursday.

The bigger question: Can he get the 218 Republican votes necessary to become speaker when the full House votes on October 29?

On Thursday, McCarthy is facing off against Rep. Jason Chaffetz (R-Utah), the chair of the powerful House Oversight Committee, and Rep. Daniel Webster (R-Florida), the upstart candidate preferred by an influential group of House conservatives.

McCarthy has come under fire by both Democrats and members of his own party after he suggested in an interview that the House's select committee investigating the 2012 terrorist attack in Benghazi had helped bring down former Secretary of State Hillary Clinton's poll numbers.

Clinton is now the Democratic front-runner for president, and she and her team have long charged the committee's investigation was a partisan attempt to bring down her candidacy.

Chaffetz said during an MSNBC interview last week that McCarthy should apologize for his comments. He then officially announced his candidacy for speaker during a "Fox News Sunday" interview days later.

"The American public wants to see a change," Chaffetz said. "They want a fresh start. You don't just give an automatic promotion to the existing leadership team. That doesn't signal change."

McCarthy suffered another blow on Wednesday, when the influential 40-plus member "House Freedom Caucus" - the group of hard-line conservatives that frequently bucked Boehner in key votes - said it would endorse Webster for speaker.

Chaffetz has said he'll support the nominee that comes out of Thursday's vote. But members of the Freedom Caucus are less predictable. Rep. Jim Jordan (R-Ohio), the group's leader, said in a statement that the group has "every intention of voting together tomorrow and on the House floor."

Here's the situation: McCarthy will almost certainly receive a majority of Republican votes to become the caucus' nominee for speaker on Thursday. But he needs 218 votes to become speaker on October 29, when the full House votes. If even 30 of the House Freedom Caucus members stick with their plan, it could force a multiple-ballot election for speaker for the first time in almost a century.

"If McCarthy secures at least 200 votes (as he has publicly stated), he should be in a consolidation phase for the remainder of October," said Chris Krueger, an analyst at Guggenheim Securities. "If he falls short of 200 votes, it would likely spell an even rockier October as he would have to appeal even more to the harder elements of the House GOP."

And that could potentially throw the House into more potential chaotic uncertainty with two key deadlines looming: The federal Highway Trust Fund, which funds numerous construction projects across the country, is set to lapse on October 29, the same day as the speaker vote.

And the Treasury Department told Congress last week that Congress needs to raise the nation's debt ceiling by November 5 to avoid a potential default on its obligations.

Said Krueger: "29 House Republicans who stay together can essentially block any Speaker candidate deemed too moderate and throw the House into chaos on the eve of the debt ceiling vote."