Republicans toiled on Tuesday to unite around a candidate for speaker on the eve of an internal party contest that has highlighted their divisions amid deep uncertainty in the House of Representatives.
Fewer than half of House Republicans had publicly announced their support for either of the leading candidates to replace former Speaker Kevin McCarthy: Representative Steve Scalise of Louisiana, the party’s second-ranking leader, and Representative Jim Jordan of Ohio, the Judiciary Committee chairman.
And there was a complicating factor: Supporters of Mr. McCarthy had begun strategizing about engineering a possible vote to reinstate him, and the former speaker said he was open to the idea.
The unsettled situation reflected deep rifts in the G.O.P. that could prolong the race and lead to a drawn-out fight on the House floor. The chamber has been paralyzed since right-wing Republicans succeeded last week in deposing Mr. McCarthy, a California Republican. Members of Congress were growing increasingly worried that the leaderless chamber could be unable to act to support Israel, after the invasion by the Palestinian militant group Hamas that has led to more than 1,000 deaths.
Representative Michael McCaul, Republican of Texas and chairman of the House Foreign Affairs Committee, said the attack on Israel had made it all the more urgent for the House to elect a new speaker quickly.
“We need to get a speaker by Wednesday,” he said, adding: “The world is watching. They’re seeing a dysfunctional democracy.”
Mr. McCaul, who has not endorsed a candidate, said he worried that in a three-way race, no one would emerge with a majority of Republican support.
“I think by and large people will accept the will of the conference, but getting to 217 — that’s going to be the issue,” he said.
Mr. Scalise and Mr. Jordan took part in a closed-door candidates’ forum on Tuesday that stretched well into the evening, with dozens of members asking questions. Mr. McCarthy said he was not a declared candidate and would not take part.
“This is a dangerous world right now,” Mr. Scalise told reporters at the Capitol, adding: “We stand strongly with Israel. The House needs to get back to work.”
But supporters of Mr. Jordan argued the chaos of last week made it clear that Republicans needed to move in a different direction that was more in tune with the party’s base.
“With all that’s gone on this Congress, it might be time for a new look at leadership,” said Representative Byron Donalds of Florida, who supports Mr. Jordan, adding: “We wouldn’t be at this place if our leadership was batting 1,000.”
Many members said they remained undecided or unwilling to endorse a candidate.
“It was helpful to hear some specific answers to some specific questions,” said Representative Daniel Crenshaw of Texas, who would not say which way he was planning to vote.
At a closed-door meeting of House Republicans on Monday evening, several speakers took aim at the eight Republican rebels who voted to oust Mr. McCarthy.
Two of those eight — Representatives Matt Gaetz of Florida and Tim Burchett of Tennessee — said afterward that they would back whomever a majority of Republicans supported.
But both said they would not accept a return of Mr. McCarthy, whom they argue proved himself untrustworthy while in leadership.
“I’m not voting for Kevin,” Mr. Burchett said, adding that he was a target of criticism at the meeting. “Some people were mad, and they’ve got a right to be mad. But I’ve got a right to represent my constituents too.”
Mr. Gaetz said the Republican conference had “two great folks running for speaker in Jim Jordan and Steve Scalise.”
But Representative Marjorie Taylor Greene, a far-right Georgia Republican who has aligned herself with Mr. McCarthy, sounded enthusiastic about the possibility of the ousted speaker’s return.
“When a group of eight joined with Democrats to oust our speaker, that was something people cheered for because they were ready for someone’s head on a platter, but it shouldn’t have been our Republican speaker,” she said, adding: “I think it was wrong what happened to Kevin McCarthy.”
Ms. Greene said Mr. McCarthy was “widely supported.”
“I think that’s a wise move to leave the door open,” she said of his current position in the race.
Republicans also were debating possible changes in their internal party rules before the vote, including one that would make it more difficult to kick out a sitting speaker, and another requiring a near-unanimous vote among members of the party before nominating a candidate for speaker. Both were attempts to avoid a repeat of the embarrassing story arc of Mr. McCarthy’s speakership, in which he suffered through 15 floor votes to gain the job in January, before he was kicked out last week.
Whoever emerges from the leadership fight, Mr. McCaul called on his fellow Republicans to look at the violence in Israel and put their differences aside.
“If we don’t have a speaker, we can’t put anything on the floor and we’re paralyzed,” he said, adding: “If that doesn’t wake up the members of my conference, then I don’t know what will.”