McCarthy is still lacking support to take over as speaker as the vote gets closer.

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Rep. Kevin McCarthy of California was still trying to acquire the votes he needed to become speaker just hours before the vote on Tuesday, and conservative opponents were preparing for a potentially tumultuous ground battle as the new House Republican majority started to take shape.

Republicans were expected to celebrate this day, but the impasse loomed over it, revealing significant divisions within the party as he begins his first week in office. Because of all that had happened, even if Mr. McCarthy had triumphed, he would still be a weak speaker who would be dependent on a strong right flank.

When the new Congress convenes on Tuesday at noon, Mr. McCarthy will face a vote in which he must be elected president by a majority of those present and voting, or 218 if every member of the House were to be present. Republicans must hold 222 seats, and Democrats will almost certainly vote heavily against Mr. McCarthy, giving him little opportunity for internal party defections.

Despite making a number of significant compromises in an effort to win over members on the "far right," Mr. McCarthy still didn't appear to have the necessary number of votes, with at least five Republicans publicly pledging their opposition to him and others privately undecided.

McCarthy resolutely told Republicans in a closed-door meeting on Tuesday, "I'm not leaving," as the leader chastised his detractors and his opponents let out their wrath, according to the members present.

Mr. McCarthy made the case that senators who disagreed with him were cynically sabotaging what was meant to be a day of togetherness for their own personal advantage in a chamber in the Capitol's basement.