Here are key moments from the fiery town-hall style presidential debate between Republican Donald Trump and Democrat Hillary Clinton at Washington University in St. Louis on Oct. 9. (Sarah Parnass/The Washington Post)

Here are key moments from the fiery town-hall style presidential debate between Republican Donald Trump and Democrat Hillary Clinton at Washington University in St. Louis on Oct. 9. (Sarah Parnass/The Washington Post)

House Speaker Paul D. Ryan (R-Wis.) told colleagues Monday he will no longer campaign for or defend GOP presidential nominee Donald Trump, even as Trump’s top advisers said he would keep up his offensive against Hillary Clinton.

In a conference call with GOP House members Monday morning, Ryan said he is “only campaigning for House seats and promoting our agenda,” according to multiple participants on the call who requested anonymity because of the sensitive nature of the topic.

Ryan’s move underscores the dilemma Republicans now face, even as Trump and his allies were buoyed by an assertive Sunday debate performance that brought the campaign into new and dark territory. They can remain in line with their nominee, which will please their base but could alienate swing voters critical to maintaining their hold on Congress, or renounce him and offend Republicans eager for a direct confrontation with both Clinton and her husband.

Rep. Greg Walden (R-Ore.), chairman of the National Republican Congressional Committee, delivered a blunt political warning to his colleagues, according to one lawmaker on the call who asked for anonymity in order to speak freely.

Walden instructed them to continue polling regularly, the member said, because the end of this campaign was like landing an airplane in a hurricane: “You have to trust the instruments.”

A handful of Republicans spoke up on Trump’s behalf, saying Clinton remained a weak candidate who can be defeated.

And in an interview Monday, former House speaker Newt Gingrich (R-Ga.), a close ally of Trump’s, said his performance would make it more difficult for Republicans to abandon him.

“They’ve really raised the ante on Republicans who want to cut and run,” he said. “How can you have watched that debate without knowing he won?”

Reeling from the release of a 2005 video showing him crudely bragging about using his fame to force himself on women, Trump sought to salvage his candidacy by dialing up his attacks on Clinton to new levels during their town hall event in St. Louis.

He repeatedly interrupted the Democratic nominee. He lashed out at her with a multitude of falsehoods over her foreign and domestic policies as well as her judgment and character. He called her “a liar” and “the Devil.” And as Clinton answered voters’ questions in the town-hall-style debate, Trump lurked just an arm’s length behind her with a grimace on his face.

Trump further claimed that Clinton was trying to discredit and humiliate women who accused her husband of sexual abuse.

Clinton, while mostly restrained, showed flashes of ire at her aggressor during their second of three face-to-face encounters before the election.

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“Okay, Donald, I know you’re into big diversion tonight,” she said. “Anything to avoid talking about your campaign and the way it’s exploding and the way Republicans are leaving you.”

[Trump went where backers begged him to avoid]

With the Republican Party in an unprecedented crisis and dozens of GOP officials calling on Trump to step aside since the video’s release on Friday, Trump’s isolation was laid bare on the stage here when he curtly broke with his vice-presidential nominee, Indiana Gov. Mike Pence, on a central foreign policy issue.

While Pence has described Russia in hawkish terms as a menace in the Middle East, Trump said he disagreed and that they had not discussed Russia’s role in the Syrian civil war.

Speaking Monday on CNN, Pence said moderator Martha Raddatz of ABC News “just mischaracterized” his earlier remarks.

“You know, the question that I got was about Aleppo, it was about humanitarian aid,” he said, adding that he and Trump back safe zones for refugees. “You need to be willing to use resources and including military power to secure those safe zones to allow those people, including 100,000 children, to be able to evacuate.

In last week’s vice-presidential debate, Pence said “the provocations by Russia need to be met with American strength.”

In both his CNN appearance and one on Fox News Channel’s “Fox and Friends” shortly before then, Pence — who will be campaigning in North Carolina and Iowa this week — said he remained proud “to stand shoulder to shoulder” with Trump.

“This election is not about any one individual, it’s about the future of the country,” he said on Fox. He added that he thought Trump had shown “humility” and “strength” on Sunday by apologizing for his 2005 remarks.

“My hope is that people across the country, including elected officials, believe in redemption as much as I do,” Pence said. While he did not plan to get on an 11 a.m. call with Republican members of Congress, he said, “I’m happy to talk to any of my friends in leadership. But really, this election is really in the hands of the American people.”

Trump was not alone in answering for his political baggage. Clinton was forced to address damaging leaks of her paid speeches to Wall Street firms as well as the investigation of her use of a private email server as secretary of state. The real estate mogul vowed to appoint a special prosecutor to investigate Clinton’s emails and handling of classified information.

Trump campaign manager Kellyanne Conway emphasized Monday that her candidate was prepared to stay on the offensive during the final weeks of the campaign.

Calling her boss’s performance “masterful” in an interview on MSNBC’s “Morning Joe,” Conway said Trump’s threat to appoint a special prosecutor essentially asks Clinton: “Why is there a separate set of rules applied to you?”

“I think that’s Donald Trump channeling the frustration he hears from thousands of voters out there on the stump every day,” she said.

After Clinton offered a critique of Trump’s fitness for office at one point during the debate, saying, “It’s just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country,” Trump interjected, “Because you’d be in jail.”

Conway called that line “a quip” on Monday.

[One for the record books]

The GOP nominee also unfurled a searing attack on former president Bill Clinton, who watchedstern-faced from the audience. He referred to a quartet that included Paula Jones, who accused Bill Clinton of sexual harassment in the early 1990s, and Juanita Broaddrick, who accused him of raping her in 1978.

“If you look at Bill Clinton, far worse,” Trump said. “Mine were words and his was action. What he did to women, there’s never been anybody in the history of politics in this nation who’s been so abusive to women. . . . Hillary Clinton attacked those same women and attacked them viciously.”

Noting that some of Clinton’s accusers were seated in the audience as his guests, Trump continued: “What President Clinton did, he was impeached. He lost his license to practice law. He had to pay an $850,000 fine to one of the women, Paula Jones, who’s also here tonight. And I will tell you that when Hillary brings up a point like that, she talks about words that I said 11 years ago, I think it’s disgraceful.”

His campaign sought to intimidate Hillary Clinton and embarrass her husband by seating those four women in his family’s box at the debate, according to four people involved in the discussions.

The campaign’s plan, which was closely held and unknown to several of Trump’s top aides, was thwarted just minutes before it could be executed when officials with the Commission on Presidential Debates intervened. The commission officials warned that, if the Trump campaign tried to seat the accusers in the elevated family box, security officers would remove the women, according to the people involved, who spoke on the condition of anonymity because the discussions were confidential.

“We had it all set,” said former New York mayor Rudy Giuliani, referring to a plan that was devised by Trump campaign chief executive Stephen K. Bannon and Trump’s son-in-law Jared Kushner and personally approved by Trump. “We wanted to have them shake hands with Bill, to see if Bill would shake hands with them.”

[The thwarted plan to embarrass Bill Clinton with his accusers]

Clinton refused to litigate the women’s allegations raised by Trump, which the Clintons have long denied. “When I hear something like that I am reminded of what my friend Michelle Obama advised us all: ‘When they go low, you go high,’ ” Clinton said, referring to the first lady.

Trump was energetic but at times confusing, stitching together scattered talking points and often evading the questions, presenting a stark contrast to Clinton’s steady if also sometimes halting and lawyerly presentation.

The evening’s caustic tone was set when Trump and Clinton refused to shake hands when they met at center stage. Trump was asked at the start of the debate whether he understood that he was effectively describing sexual assault in the newly released video. His voice flat, Trump framed the matter as a distraction from the problems facing the world.

“I’m very embarrassed by it,” Trump said. “I hate it. But it’s locker-room talk. It’s one of those things. I will knock the hell out of ISIS.”

Clinton responded: “What we all saw and heard on Friday was Donald talking about women, what he thinks about women, what he does to women. And he has said that the video doesn’t represent who he is, but I think it’s clear to anyone who heard it that it represents exactly who he is.”

[Trump wanted family box access for women accusing Bill Clinton]

The debate, co-moderated by Raddatz and Anderson Cooper of CNN, was a turbo-charged spectacle in an electric campaign. Trump touched down Sunday in St. Louis a defiant and angry nominee, more isolated from his party than any other in modern times.

Trump spent the weekend mostly hunkered down at Trump Tower in New York, stewing over mass defections from fellow Republicans and taking counsel from a shrinking circle of loyalists. His candidacy has plunged the GOP into civil war and elected officials fearing he could cost them their majorities in both chambers of Congress.

Trump’s candidacy was in a precarious state even before Friday’s release of the video showing his predatory remarks. After stumbling through the first debate and behaving erratically in the aftermath, Trump fell behind Clinton in most national and battleground state polls.

Clinton was challenged by Trump over the leak of her campaign aides’ emails containing transcripts of her paid speeches to a variety of financial firms. They showed Clinton talking about taking different positions in private than she did in public.

Clinton defended herself in a halting and lawyerly fashion and brought up former president Abraham Lincoln, who was portrayed as a deal-maker who embraced political compromise in a Steven Spielberg film. She said that portrayal inspired her to make the comment in private.

Trump wanted none of it: “Now she’s blaming the late, great Abraham Lincoln,” he said, rolling his eyes. “Honest Abe never lied. That’s a big difference between Abraham Lincoln and you. That’s a big, big difference.”

One of the more visceral moments came when a Muslim woman asked a question about Islamophobia. That led to a discussion of perhaps the most controversial policy proposal advanced by Trump: An immediate and temporary ban on foreign Muslims entering the United States.

When told that Pence said the Muslim ban was no longer operable, Trump said the policy “is something that, in some form, has morphed into an extreme vetting from certain areas of the world.” But when Raddatz pressed him for specification, Trump would not say what it had morphed into beyond “extreme vetting.”

Clinton also used Trump’s affinity for Russian President Vladi­mir Putin to cast the Republican nominee almost as a pawn for an adversarial foreign power. Clinton said Russia was “working so hard” to influence the U.S. election.

“Maybe because he has praised Putin,” she said, demanding that Trump release his tax returns that would show whether he has any conflicts of interest with Russia or other foreign entities.

“So ridiculous,” Trump said. “I don’t know Putin. . . . I know nothing about Russia.”

Also Sunday, Trump seemed to concede that he had avoided paying any federal income taxes for some recent years by taking advantage of tax loopholes and the massive $916 million loss he reported in 1995.

Eilperin reported from Washington. Paul Kane, Kelsey Snell and Karen Tumulty in Washington contributed to this report.