CNN
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The new House Republican majority faces a once-in-a-century fight to elect the next speaker after GOP leader Kevin McCarthy failed to lock down the votes needed to win in the first round of voting. The chamber is voting on a second ballot, something that hasn’t happened since 1923.

The outcome of Tuesday’s initial vote, taking place on the first day of the 118th Congress, is a major blow that throws into question whether McCarthy will be able to win the speaker’s race, though the GOP leader has vowed to stay in the race.

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The new House Republican majority is now facing a contentious, drawn-out fight that threatens to deepen divides within the party with McCarthy’s political career on the line. And the deal-making McCarthy has engaged in to try to win over critics may mean he has a weaker hand to play in his position of authority if he does become speaker.

Sources with knowledge of McCarthy’s thinking say he is still confident that he will eventually get the 218 votes to be elected. But there is no way of guessing how long the voting will go or how many ballots it will take.

McCarthy remains defiant in the face of opposition, with people close to him summing up his mentality as this: “We’re going to war,” a senior GOP source tells CNN. “Never backing down.”

The obstacle for McCarthy is that he faces a small but determined contingent of hardline conservatives. The group is using the leverage they have in the razor-thin Republican majority to extract concessions as they threaten to deny the GOP leader critical votes. McCarthy has already given in to a number of their demands, including making it easier to topple the sitting speaker, but it is unclear whether his efforts will be enough.

To be elected speaker, a candidate needs to win a majority of members who vote for a specific person on the House floor. That amounts to 218 votes if no member skips the vote or votes “present.”

House Republicans hold 222 seats in the new Congress – so for McCarthy to reach 218, he would only be able to afford to lose four GOP votes.

The tally for the first ballot in the speaker vote was 203 for McCarthy, with 19 Republicans voting for other candidates.

The 19 Republicans who voted against McCarthy in the first ballot are considering all voting for GOP Rep. Jim Jordan on the second ballot, sources tell CNN.

But Jordan, to show that he is not vying for the job, nominated McCarthy ahead of the vote on the second ballot.

A closed-door meeting of House Republicans on Capitol Hill grew tense and heated Tuesday morning as uncertainty grew over McCarthy’s fate.

McCarthy raised his voice and was animated as he teed off against his opponents and detailed concessions he has made, according to two sources. “I’ve earned this job,” he said.

After the far-right House Freedom Caucus denied his ascension to the speakership in 2015, McCarthy spent years courting the conservative wing of his party and worked hard to stay in former President Donald Trump’s good graces.

McCarthy has gotten some key backup from Trump, who publicly endorsed his speaker bid and encouraged others to support McCarthy. His congressional allies have also banded together in effort to act as a counterweight to his critics.

But when a red wave never materialized in the November midterms, the razor-thin majority that resulted for Republicans empowered a small band of conservatives – long distrustful of McCarthy – to make demands.

What has unfolded over the last two months is an all-out scramble for the speakership, which has taken the form of strategy sessions with close allies on and off Capitol Hill, intense negotiations over rules changes and non-stop phone calls with members.

McCarthy has been in deal-making mode, but if he does win the gavel, some of the concessions he has made may make it more difficult for him to stave off future challenge to his speakership.

In one change that could weaken his hand in the future, McCarthy has told lawmakers – as first reported by CNN – that he would support a threshold as low as five Republicans to trigger a vote on deposing the speaker, known as the “motion to vacate” the speaker’s chair, a major concession for him and one that moderates worry will be used as a constant cudgel over his head.

This story and headline have been updated with additional developments Tuesday.