The conservative House Freedom Caucus on Wednesday endorsed little-known Rep. Daniel Webster (R-Fla.) for Speaker  — a bold move that raises serious doubts about whether Majority Leader Kevin McCarthy can cobble together the 218 votes on the House floor he needs to be promoted.

McCarthy, a five-term California Republican, is expected to easily win the nomination when House Republicans huddle at noon Thursday to pick a successor to outgoing Speaker John BoehnerJohn Andrew BoehnerHouse Dem: Party's aging leaders is 'a problem' Women poised to take charge in Dem majority Freedom Caucus ponders weakened future in minority MORE (R-Ohio).

But the true test will come Oct. 29, when the House holds a public roll call vote to formally elect the next Speaker.

The Freedom Caucus, led by Chairman Jim Jordan (R-Ohio), holds enough votes to essentially veto a McCarthy Speakership, though it’s unclear whether all members would cast their ballots the same way.

No one can be elected Speaker unless they win 218 votes. 

“I think he’s over the 200 hump, but that’s not the hump,” said Rep. Lynn Westmoreland (R-Ga.), a McCarthy backer who acknowledged the leader still has a steep climb.

Webster, 66, the soft-spoken former Speaker of the Florida House, is a long shot to win the Speaker’s gavel, as is another rival, Oversight Committee Chairman Jason ChaffetzJason ChaffetzMatt Schlapp: Trump's policies on Russia 'two or three times tougher than anything' under Obama Tucker Carlson: Ruling class cares more about foreigners than their own people Fox's Kennedy chides Chaffetz on child migrants: 'I’m sure these mini rapists all have bombs strapped to their chests' MORE (R-Utah), 48, who jumped into the race last weekend.

But combined, Webster and Chaffetz easily could siphon more than 30 GOP votes from McCarthy on the House floor, denying him the Speaker’s gavel and sending the process into multiple rounds of voting.

And the endorsement of Webster signals the influential 40-plus member Freedom Caucus’s intention to draw out the process and force McCarthy’s hand.

“Under the present circumstances and without significant changes to Conference leadership and process, Rep. Daniel Webster would be best equipped to earn back the trust of the American people as Speaker of the House,” the group said in a joint statement. 

Rep. Mick Mulvaney (R-S.C.), a Freedom Caucus member, said the endorsement is for Thursday’s vote and not for the floor vote.

Still, he said the group has proven that “once we walk out of that room united, we stay united on the floor.”

With the math working against McCarthy, some conservative leaders are reviving the idea of brokering a deal and forging a coalition with the GOP leader: A bloc of conservatives would throw their support to McCarthy on the House floor, pushing him over 218. In return, McCarthy would back one of the conservatives, such as Jordan, to replace him as majority leader.

“Getting a majority of the conference for Speaker is not the answer. He’s got to get to 218 on the floor,” said one leader of the Freedom Caucus, which had pressured BoehnerJohn Andrew BoehnerHouse Dem: Party's aging leaders is 'a problem' Women poised to take charge in Dem majority Freedom Caucus ponders weakened future in minority MORE to resign. “There is speculation among many that the only way that Kevin McCarthy ever gets 218 on the floor is if there are different people in leadership.”

Mulvaney called the idea of a conservative coalition with McCarthy “something that is still on the table.”

“I can foresee a situation where that might gain some broad support from the conference,” he said.

Senior GOP aides see such a coalition as improbable. And Jordan has said he has no desire to serve in leadership.

But some Jordan allies say they could see a scenario where the former Republican Study Committee (RSC) chairman would reluctantly run for the No. 2 job. Majority Whip Steve Scalise (R-La.) and Budget Committee Chairman Tom Price (R-Ga.), two other past RSC chairmen, are already running hard for majority leader, but there’s dissatisfaction among some conservatives with the current choices. Elections for the leader job would only be held if McCarthy is elected Speaker and a vacancy opens up.

“In the right circumstances, Jim would probably step up and do it,” the Freedom Caucus lawmaker said.

McCarthy allies are urging their colleagues to unify around whoever emerges from Thursday’s vote on the House floor. “If you’re going to be a member of the conference, you ought to support the conference nominee,” said Rep. Tom Cole (R-Okla.), a McCarthy supporter and former member of leadership.

But the public roll call, where lawmakers will have to shout out the name of their candidate for Speaker on live TV, is sure to create headaches for many Republicans. Twenty-five voted against Boehner for Speaker in January.

And conservatives inside and outside of the Capitol are trying to suggest that a vote for McCarthy is another vote for Boehner, a creature of Washington who’s despised by the base. The Tea Party-aligned FreedomWorks is blasting McCarthy as “Boehner 2.0.”

Rep. Thomas Massie (R-Ky.), who is backing Webster, predicted more Republicans would vote for McCarthy in Thursday’s internal election rather than on the House floor.

“This is like the Boehner vote part two. You want to go home and tell your constituents you voted for Boehner’s right-hand man?” Massie said. “It’s easier to do that in a private, secret ballot behind closed doors than in public.”

Even some natural leadership allies such as Rep. Renee Ellmers (R-N.C.) expressed doubts about promoting McCarthy to Speaker, a job second in line to the presidency.

“He has not spoken to me personally for my vote, and Jason Chaffetz has, so that’s where I am right now. At this point I will be casting a vote for Jason Chaffetz,” said Ellmers, who is facing a GOP primary challenger. “I can’t vote for someone who doesn’t ask for my vote.

“I’m apparently not high on his priority list,” she added.

Complicating matters is the fact that McCarthy has been contending with a media firestorm of his own making. On Fox News last week, the GOP leader suggested the Republican-led committee investigating the 2012 Benghazi attacks was created to help deflate Hillary ClintonHillary Diane Rodham ClintonArizona GOP Senate candidate defends bus tour with far-right activist Santorum: Mueller could avoid charges of McCarthyism by investigating DOJ, FBI Giuliani claims McGahn was a 'strong witness' for Trump MORE’s presidential poll numbers.

Even close McCarthy friends said his remarks were damaging to the party. Benghazi Committee Chairman Trey GowdyHarold (Trey) Watson GowdyFBI chief: I'm trying to bring 'normalcy' in 'turbulent times' Jim Carrey targets McCarthy, Nunes ahead of midterms House GOP prepares to grill DOJ official linked to Steele dossier MORE (R-S.C.), who himself has been mentioned as a dark-horse leadership candidate, said on MSNBC that McCarthy flat-out “screwed up.” “Not good. That’s what I can say. Not good.”

Before the Freedom Caucus endorsement Wednesday, Jordan hinted that his group planned to wield power by voting as a bloc in the Speaker’s race.

“We have every intention of voting together tomorrow and on the House floor,” he said.

The next three weeks could offer time for conservatives to rally behind a majority leader candidate more preferable than Scalise or Price. But so far, no one is prepared to launch a bid themselves.

Rep. Raúl Labrador (R-Idaho), a founding member of the Freedom Caucus, said the group’s best shot at influencing the races at this point is by banding together.

“That’s really our strength right now, is working together as a group,” said Labrador, whom McCarthy handily defeated in the race to succeed Majority Leader Eric CantorEric Ivan CantorHillicon Valley: GOP leader wants Twitter CEO to testify on bias claims | Sinclair beefs up lobbying during merger fight | Facebook users experience brief outage | South Korea eyes new taxes on tech Sinclair hired GOP lobbyists after FCC cracked down on proposed Tribune merger California wildfires prompt deficit debate in Congress MORE (R-Va.), who unexpectedly lost his 2014 primary. “And I’ll be honest, I don’t know if any of our leading members could be elected right now.”

Updated at 8:19 p.m.