One member, Representative Dana Rohrabacher of California, attacked Republicans stepping away from Mr. Trump as âcowards,â three lawmakers said. Another, Representative Trent Franks of Arizona, used graphic language to describe abortion and said allowing Mrs. Clinton into the White House would end with fetuses being destroyed âlimb from limb.â
How the two top Republicans in Congress have responded to Mr. Trumpâs comments.
In an effort to quiet the uproar, Mr. Ryan chimed back in after about 45 minutes to assure members that he was not withdrawing his endorsement of Mr. Trump, but rather doing what he considered to be in the best interests of the House.
Mr. Trump appeared indifferent to the distinction, lashing back at Mr. Ryan with a belittling message on Twitter.
âPaul Ryan should spend more time on balancing the budget, jobs and illegal immigration and not waste his time on fighting Republican nominee,â Mr. Trump wrote in his Twitter post.
AshLee Strong, a spokeswoman for Mr. Ryan, confirmed that his sole priority for the remainder of the election would be defending congressional Republicans.
âThe speaker is going to spend the next month focused entirely on protecting our congressional majorities,â Ms. Strong said.
Ms. Strong said there was âno updateâ regarding Mr. Ryanâs endorsement of Mr. Trump.
The breach between Mr. Ryan and Mr. Trump concluded five months in which the two men have alternated between friction and courtship, eventually forging an uneasy working relationship only to see it collapse in the final weeks of the race.
Graphic: More Than 160 Republican Leaders Donât Support Donald Trump. Hereâs When They Reached Their Breaking Point.
The consequences for both men are enormous. Mr. Ryan and other Republican leaders fear that Mr. Trumpâs flagging campaign could unwind their majorities in the House and Senate, while Mr. Trump can ill afford rejection from more prominent Republicans.
Mr. Trumpâs candidacy was already in a dire condition before Mr. Ryanâs announcement. A poll published Monday by NBC News and The Wall Street Journal found him trailing Mrs. Clinton by a wide margin and drawing less than 40 percent of the vote. The survey was taken before Sunday nightâs debate.
Representative Scott Rigell of Virginia, a Republican who has long been opposed to Mr. Trump, said there was a general sense in the House that more humiliating disclosures about Mr. Trump were likely to come before Nov. 8, Election Day.
âThereâs a consensus, even among supporters, that the likelihood of something else breaking in a very embarrassing and negative fashion, is certainly better than 50-50,â said Mr. Rigell, who joined the call on Monday. âThe conference, members, et cetera, are bracing themselves for another salvo of this.â
Speaking to reporters aboard Mrs. Clintonâs campaign plane on Monday, Jennifer Palmieri, her communications director, made it clear the campaign intented to tie down-ballot Republicans to Mr. Trump with a new fervor â after months of casting his candidacy as a dangerous anomaly.
âThere was a time where they could have stopped Donald Trump. There was a time where they could have spoken out against him,â Ms. Palmieri said of senior Republicans like Mr. Ryan. âThat time was this summer. Obviously it is too late now.â
Mr. Trumpâs campaign had hoped that the debate would halt an exodus of fellow Republicans from his candidacy, and it publicly implored members of the party on Monday morning to hang with him through Election Day.
In an effort at reassurance, Gov. Mike Pence of Indiana, Mr. Trumpâs running mate, toured the morning television shows to tamp down speculation that he might leave the ticket. At a campaign stop in North Carolina, Mr. Pence said he was âproud to stand with Donald Trump.â
But in a potentially ominous sign for the party, Kellyanne Conway, Mr. Trumpâs campaign manager, also offered a note of warning for Republicans fleeing Mr. Trump. Mr. Ryan, she noted on television, had been booed by Trump fans over the weekend in Wisconsin after asking Mr. Trump not to attend a political event in his home state.
Ms. Conway also repeatedly indicated that she was aware of Republican lawmakers who had behaved inappropriately toward young women, and whose criticism of Mr. Trump was therefore hypocritical.
Mr. Ryanâs huddle with House Republicans was the first of multiple war councils in Washington on Monday, as Republicans weighed how to handle a nominee whose campaign has appeared to unravel in recent days.
The Republican National Committee, which has been fiercely loyal to Mr. Trump, was to hold a conference call with its members later in the afternoon. In contrast to the mounting defections from Mr. Trumpâs campaign among Republican elected officials, the party chairman, Reince Priebus, has remained close to Mr. Trump and flew with him to the debate in St. Louis over the weekend.
Credit Mandel Ngan/Agence France-Presse â Getty Images
As telling as the fury from outspoken conservatives in the House was the silence from so many mainstream Republicans in the chamber, who showed little appetite to argue for or with their embattled nominee.
Few anti-Trump voices spoke up on the call with Mr. Ryan. Representative Martha Roby of Alabama, a defector from Mr. Trump on Saturday, said she would contribute significant funds to help Republicans hold the House majority. But she said she would speak with colleagues in private about her decision to withdraw her endorsement in the presidential race.
Representative Charlie Dent of Pennsylvania, a vocal critic of Mr. Trump, asked his colleagues if they were truly confident that there would be no more damaging disclosures about Mr. Trump. In any case, Mr. Dent argued that the presidential race was now effectively over for Mr. Trump.
No new prominent Republicans have withdrawn their endorsements from Mr. Trump since the end of the debate, but there was a palpable fear throughout the party that Mr. Trump had already been damaged beyond repair.
Representative Greg Walden of Oregon, chairman of the National Republican Congressional Committee, urged members on the conference call to take new polls in their districts to gauge the impact of Mr. Trumpâs political slide.
Mr. Walden said they should brace for a steep erosion of support for Mr. Trump and acknowledged the falloff could undermine congressional candidates, too. He asked the entire caucus to contribute quickly to the partyâs campaign arm, making it clear they needed to bolster their defenses across the country.
Still, many members were pointed in their expressions of dismay, warning Mr. Ryan of grave consequences, in November and beyond, if Mr. Trumpâs campaign collapses altogether. Representative Billy Long of Missouri spoke up in Mr. Trumpâs defense, citing the danger of losing the Supreme Court in the event of a Clinton victory.
âMany of us commented that if Hillary picks the next two to four judges, it will change the fabric of our country of 40, 50 years,â Mr. Long said of the call. âAbortion and the Second Amendment, also, and lots of Supreme Court concerns.â
Correction: October 10, 2016
An earlier version of this article misstated the number of women whom Donald J. Trump held a press conference with to accuse Bill Clinton of sexual misdeeds. It was three, not four. A fourth woman at the event criticized Hillary Clinton for providing legal representation for an accused child rapist.