At a rally in Wilkes-Barre, Pa., Oct. 10, Republican presidential nominee Donald Trump said he might make six campaign stops a day during the week leading up to Election Day. (The Washington Post)

The Republican Party tumbled toward anarchy Monday over its presidential nominee, as House Speaker Paul D. Ryan (Wis.) cut Donald Trump loose in an emergency maneuver to preserve the party’s endangered congressional majorities.

Ryan’s announcement that he would no longer defend or campaign with Trump prompted biting condemnations from within his caucus and from Trump himself, who publicly lashed out at the speaker.

It was an extraordinary display of personal animus just four weeks before the election, destroying any semblance of party unity behind a nominee who many GOP leaders said they could no longer stomach because of his character traits and tawdry campaign tactics.

New national and battleground-state polls showed Trump sliding since Friday’s publication of a 2005 video of him bragging about sexual assault, putting Clinton in position for a possible electoral landslide. Clinton surged to an 11 percentage point lead nationally in an NBC News-Wall Street Journal poll conducted over the weekend.

“It’s every person for himself or herself right now,” former senator Judd Gregg (R-N.H.) said. “The nominee for president is so destructive to everyday Republicans.”

Paul Ryan told a crowd at a fall festival in Wisconsin that there was a “troubling” "elephant in the room,” after the Washington Post revealed a 2005 recording of Trump speaking in very lewd terms about women. (The Washington Post)

Republican National Committee Chairman Reince Priebus pledged complete fidelity to Trump in a conference call with RNC members and denied rumors that the national party was redirecting its resources to down-ballot races, according to a person on the call.

With Republicans at war among themselves, Democratic nominee Hillary Clinton moved swiftly Monday to pry away moderate Republican-leaning voters who are turned off by Trump. Her campaign launched an advertising blitz featuring testimonials from ordinary Republicans explaining why they were voting for Clinton.

“She is reaching out to voters that may well have supported Mitt Romney in 2012 and in a normal year might also be inclined to support the Republican nominee but are so troubled by Donald Trump they are open to supporting Hillary Clinton,” Clinton spokesman Brian Fallon said. He added that nasty personal attacks by Trump at Sunday’s second presidential debate in St. Louis “only helped us close the sale.”

Ryan’s move, announced on a contentious conference call with House GOP members, was seen as a concession that Trump could no longer win the presidency and that the party must devote itself to retaining its majorities in the House and Senate.

Unlike Ryan, Senate Majority Leader Mitch McConnell (R-Ky.) was rendered mute on the subject Monday. He told a business group in Kentucky that if they wanted to hear his thoughts on Trump, they “might as well go ahead and leave,” according to the Associated Press.

Still, there was no wave of defections Monday from Trump, who in an aggressive performance in Sunday night’s debate reassured the conservative base that he would be a relentless aggressor against the party’s shared enemies: Clinton and her husband, former president Bill Clinton. Trump leveled a stream of harsh charges at Hillary Clinton during the event, claiming she attacked women who accused her husband of sexual abuse and promising to send the former secretary of state to jail if he is president.

“They’ve really raised the ante on Republicans who want to cut and run,” said former House speaker Newt Gingrich (R-Ga.), a Trump ally. “How can you have watched that debate without knowing he won?”

One important conservative who was enthused was Indiana Gov. Mike Pence, the vice-presidential nominee, who made clear Monday that he would be loyal soldier even as their campaign took a dark turn.

Campaigning in Charlotte, Pence said that he does not condone what Trump said in the 2005 video, but that as a man of faith “I believe in forgiveness.”

Trump, he added, “showed the American people what’s in his heart. He showed humility to the American people and then he fought back and turned the focus to the choice that we face, and I’m proud to stand with Donald Trump.”

But Democrats insisted that Trump’s lewd comments and description of predatory behavior in the video would haunt him for the remainder of the campaign.

“It’s not behind him,” said Sen. Claire McCaskill (D-Mo.). “No. I guarantee you. Women do not forget being talked about that way, because all women have had a man in their life who has been in a position of power that has treated them without respect.”

Many Republican elected officials felt paralyzed Monday, disgusted with Trump’s candidacy but afraid to withdraw their endorsements and feel the wrath of his supporters. The situation was most precarious for politicians in battleground states such as Florida, Ohio and Pennsylvania, who can save their seats only if they get votes from the most fervent Trump supporters as well as moderates uneasy about him.

Rep. Greg Walden (Ore.), chairman of the National Republican Congressional Committee, told House members on the conference call with Ryan that navigating the election was now like “landing an airplane in a hurricane,” according to a lawmaker on the call who spoke on the condition of anonymity to speak candidly.

Trump is exacerbating the tensions by rebuking any Republican who betrays him and using the party leadership as a foil. Trump tweeted on Sunday: “So many self-righteous hypocrites. Watch their poll numbers — and elections — go down!”

Trump’s high command is keeping track of Republicans who break from the nominee. As he climbed into a waiting SUV late Sunday in St. Louis with other Trump advisers, former New York mayor Rudy Giuliani coolly said that Trump “will remember” who was with him and who was not — and vowed that the outsider candidate would win the White House irrespective of the party leaders’ wishes.

On Monday, Ryan was at the center of the GOP’s existential crisis. The norms and ideological orthodoxy that have shaped his career no longer define the party or provide him with the means of counterbalancing Trump. So instead of directly confronting Trump, Ryan sought a middle ground by personally backing away from Trump without rescinding his endorsement.

On the call, Ryan instructed fellow House Republicans to make their own calculations about Trump based on the politics of their districts. The speaker was challenged by at least a half-dozen members, from California to Ohio, who bristled at any attempt to distance the party from Trump, people on the call said.

“He got huge pushback like I’ve never seen before from members from across the country just saying that was the wrong move — and even if it cost them the House,” said one lawmaker on the call, who, as others who were interviewed, spoke on the condition of anonymity to candidly describe the private discussion.

Late in the call, Ryan got back on the line to respond to the criticism by assuring his conference that he would not take back his endorsement, though that offered little assurance to the pro-Trump contingent.

Trump publicly chastised the speaker, tweeting, “Paul Ryan should spend more time on balancing the budget, jobs and illegal immigration and not waste his time on fighting Republican nominee.”

Rep. Charlie Dent (R-Pa.), who has called on Trump to step aside, vented his frustrations in an interview. “I for one am getting a little tired of being told that I have to fall in line and behave,” Dent said. “I’m not the one making all these outlandish and incendiary comments. People should stop screaming at the firefighters.”

Trump has done little to put the fire out. He and his campaign have fully committed to a final month of harsh combat by airing allegations of sexual assault by Bill Clinton.

Following Sunday’s debate, Omarosa Manigault, Trump’s African American outreach director, brought up Clinton’s affair with Monica Lewinsky to reporters and accused the 42nd president and his wife of having “preyed on this intern” and “destroyed her as a human being.”

“This is not a couple you want in the White House,” Manigault said. “People say, ‘Oh, Hillary’s separate from her husband.’ But if you get Hillary in the White House, you also get Bill, and Lord have mercy on us if we have to go through four more years of that.”

This approach is galvanizing Trump’s grass-roots supporters. Steven Mnuchin, Trump’s national finance chairman, said the campaign received “a big surge” of small-dollar donations and positive feedback from the debate.

“I’m getting calls all day from people who want to come to the Vegas debate and want the excitement of what people expect will be another great debate,” Mnuchin said, referring to the Oct. 19 debate in Las Vegas.

On the stump Monday in Ambridge, Pa., Trump broadened the scope of his critique to taint the entire Democratic Party as sordid, recounting the late senator Edward M. Kennedy’s 1969 car crash that killed a 28-year-old woman on Chappaquiddick Island, Mass.

Trump’s blistering method is being orchestrated by Stephen K. Bannon, the campaign’s chief executive and former head of the acerbic conservative website Breitbart, who has become a near-omnipresent counselor at Trump’s side. He has urged Trump not to worry about any cleavage in party ranks and instead to target Clinton.

For her part, Clinton seized on Trump’s negativity as a way to taunt him and argue that he is unfit to be president.

“Donald Trump spent his time attacking when he should have been apologizing,” Clinton said in Detroit in reference to the debate. “Now, there are a lot of things he should apologize for, right?”

Mike DeBonis, Juliet Eilperin, Paul Kane, Kelsey Snell and Karen Tumulty contributed to this report.