The Washington Post’s Jenna Johnson explains what the stakes are for Donald Trump’s presidential campaign following the release by The Post of a 2005 video in which he makes vulgar comments about women. (Bastien Inzaurralde/The Washington Post)

The Washington Post’s Jenna Johnson explains what the stakes are for Donald Trump’s presidential campaign following the release by The Post of a 2005 video in which he makes vulgar comments about women. (Bastien Inzaurralde/The Washington Post)

With less than a month to go before the election, a major political party is poised to walk away from its own presidential nominee — a situation with few precedents in American political history.

There is little to guide Republicans, collectively and individually, except the growing realization that they have risked their party’s survival by tying it to Donald Trump as he has led them into a crisis that is both extraordinary and utterly predictable.

Now the challenge is how to isolate and quarantine their standard-bearer so that GOP candidates up and down the ballot will not be infected by the public revulsion toward lewd comments he made about women in a newly revealed 2005 recording.

Grim GOP strategists now worry that Trump could suffer a bigger loss on Nov. 8 than they previously feared, causing spillover into down-ballot races once thought secure for Republican candidates. That means their control of the Senate is in even greater jeopardy; some doomsayers have begun to speculate that even their House majority may be in danger.

They also fear further bombshells before the election, given how much of his adult life Trump has spent within range of a microphone. “You think this is the last piece of oppo they’ve got?” one GOP strategist fretted as he contemplated the mountains of material that might be out there and available to Trump’s foes and the media.

In the wake of a new Washington Post report showing Republican presidential nominee Donald Trump speaking in very lewd terms about women in 2005, some Republicans are calling for Trump to step down as nominee. (Thomas Johnson/The Washington Post)

Republicans’ realistic options for putting a hygienic distance between the party and the man who will represent it at the top of the ticket, however, are limited.

And doing so raises the danger of igniting an intraparty civil war and alienating Trump’s legions of passionate supporters, who are drawn to the incendiary outsider in part because they are disenchanted with mainstream GOP leadership.

Republican leaders have been nearly unanimous in their denunciations of Trump’s vulgar language and his boast that he felt entitled by his celebrity to make unwanted sexual advances.

But many party elders, elected officials and donors are arguing publicly and privately that Republicans must go further in isolating or even abandoning Trump.

Growing numbers of prominent GOP figures are publicly revoking their support for the party’s nominee, and some are urging that he be replaced at the top of the ballot by his running mate, Gov. Mike Pence of Indiana.

“Donald Trump should withdraw and Mike Pence should be our nominee effective immediately,” Sen. John Thune (R-S.D.) tweeted from his official account early Saturday afternoon.

In doing so, Thune became the first member of the Senate Republican leadership to urge Trump to step down. Thune serves as chairman of the Senate Republican Conference, the third-ranking position in the party’s leadership team.

1 of 28 Full Screen Autoplay Close Skip Ad × These Republicans cut ties with Trump after lewd remarks View Photos Following a Friday report by The Washington Post on a 2005 video of the GOP presidential nominee, various Republicans have said they no longer plan to vote for him and some call for him to drop out. Caption Following a Friday report by The Washington Post on a 2005 video of the GOP presidential nominee, various Republicans have said they no longer plan to vote for him and some call for him to drop out. Sen. John McCain Sen. John McCain (R-Ariz.) joined the cavalcade of Republicans withdrawing their support for Trump. “There are no excuses for Donald Trump’s offensive and demeaning comments in the just released video; no woman should ever be victimized by this kind of inappropriate behavior. He alone bears the burden of his conduct and alone should suffer the consequences,” McCain said in a statement. Susan Walsh/AP Buy Photo Wait 1 second to continue.

The South Dakota senator had endorsed Trump in May, saying: “We have to get it right in 2016 because the future of our country is hanging in the balance in so many different ways.”

Other Republican lawmakers also joined the chorus for Trump to drop out. Among them: Senators Mike Lee of Utah and Mike Crapo of Idaho and Reps. Martha Roby of Alabama and Jason Chaffetz of Utah.

“I’m out,” Chaffetz said in a televised interview Saturday. “I can no longer in good conscience endorse this person for president.”

Carly Fiorina, a former Republican presidential candidate, tweeted: “Today I ask Donald Trump to step aside and for the RNC to replace him with Gov. Mike Pence.”

For those who must share the ballot with Trump this year, the rallying cry has become everyone for himself — or herself.

“I think each person running for election has to make his or her decision about what is best, and act accordingly,” said Fred Malek, a major fundraiser and finance chairman of the Republican Governors Association. “I don’t think there is one formula that works for all.”

Sen. Kelly Ayotte (R-N.H.), who is in a difficult reelection battle, issued a statement Saturday declaring that she plans to write in a vote for Pence as president.

“I wanted to be able to support my party’s nominee, chosen by the people because I feel strongly that we need to change the direction of the country,” Ayotte said. “However, I’m a mom and an American first and I cannot and will not support a candidate for president who brags about degrading and assaulting women.”

Sen. John McCain (R-Ariz.), the party’s 2008 presidential nominee and a candidate this year for a sixth term in the Senate, announced that he and his wife, Cindy, also will write in a candidate — “some good conservative Republican who is qualified to be President” — rather than vote for Trump.

Practically speaking, there is no way for the party to rid itself of a nominee this late in the election season, short of Trump voluntarily dropping out of the race — something the celebrity real estate magnate declared Saturday that he would “never” do.

Many states have printed their ballots, and 400,000 early and absentee votes have already been cast, according to a tally by the United States Elections Project. The party would have to persuade states to put the new nominee on the ballot by appealing to secretaries of state and seeking emergency injunctions through the courts — no easy lift at this late date.

And even if Trump did withdraw, “it’s not like Pence automatically becomes the nominee,” said Nathaniel Persily, a constitutional law expert at Stanford Law School. “Remember poor old Ted Cruz,” the senator from Texas who came in second in the GOP primaries.

Major donors and party leaders are privately — and frantically — looking for options to salvage the GOP congressional majority, which is their largest since the New Deal era.

One longtime party fundraiser put it this way Saturday: “The entire donor community is pulling back” from Trump, redirecting efforts and resources to Senate and House races.

Former Minnesota representative Vin Weber was blunt in describing the mood of the series of conversations he has had with fellow Republicans.

“The presidency has been lost, but the Congress and the party can be saved,” he said in an interview with The Washington Post. “We need to immediately focus all resources on the Congress, try to replace Trump and, failing that, settle on one alternative for principled Republicans to vote for, be it an existing third party or an agreed upon write-in candidate.”

He hailed reports that the Republican National Committee has started to halt spending on some Trump-related election efforts, at least temporarily.

“That’s a very good sign,” Weber said, hoping it would be one factor of several that might lead Trump to resign. “It means that regardless of what happens [to Trump], we will immediately shift resources to Senate and House races.” He said that focus would inspire a discouraged donor base to provide resources and call attention to real strength that still exists in the GOP.

Weber has been talking with RNC members and others about encouraging Pence to resign temporarily from the ticket, in hopes it would lead Trump to quit. He called it “the nuclear bomb.”

For many in the party, however, it feels as if the bomb has already gone off. Now, the question is how to deal with the fallout.