In the world of Republican super PACs, strategists are going even further: discussing advertisements that would treat Trump’s defeat as a given and urge voters to send Republicans to Congress as a check on a Hillary Clinton White House. The discussions were described by officials familiar with the deliberations, several of whom spoke on the condition of anonymity about confidential planning.

For Republicans in close races, top strategists say, the issue is no longer in doubt. One House Republican has already started airing an ad vowing to stand up to Trump if he is elected president, and others are expected to press similar themes in the weeks ahead.

After a disastrous week of feuds and plummeting poll numbers, Republican leaders have concluded that Donald Trump is a threat to the party’s fortunes and have begun discussing how soon their endangered candidates should explicitly distance themselves from the presidential nominee.


For now, some of the party’s most vulnerable incumbents are simply hoping to avoid what they see as the taint of association with their standard-bearer.

Two members of Congress locked in competitive races made themselves scarce when Trump arrived in their states Friday. The two, Senator Ron Johnson of Wisconsin and Representative David Young of Iowa, held events elsewhere.

Senator Patrick J. Toomey of Pennsylvania, in a conference call with reporters the same day, was less subtle. “Donald Trump is in a category unto himself,” Toomey said, predicting that his state’s voters “will make a completely separate decision” between the top of the ticket and the Senate campaign this year.

That is increasingly the hope of nearly every Republican leader across the country.

Trump’s plunge in polls this past week, along with his dual attacks on the family of a fallen US soldier and the leadership of his own party, has convinced veteran Republican strategists that most of their candidates must navigate around the presidential nominee.


Plans for ads that distance congressional candidates from the top of the ticket have accelerated. “You will see them by early to mid-September now,” even before the first debate on Sept. 26, predicted Scott Reed, senior political strategist for the US Chamber of Commerce.

At a recent conference of Republican donors, Paul D. Ryan, the speaker of the House, warned that even the party’s substantial majority in that chamber might be in jeopardy.

“The conclusion has become that the guy is incorrigible,” said Thomas M. Davis III, a former House member from Virginia who is still close to many of the party’s leaders. “He’s going to leave our candidates with no choice but to go their own separate way.”

Trump’s campaign did not respond to requests for comment, but Friday night he tried to calm angry Republicans by endorsing, belatedly, the reelections of Ryan and senators John McCain of Arizona and Kelly Ayotte of New Hampshire. Trump had been feuding with them after they criticized his ridicule of the parents of Humayun Khan, a Muslim American Army captain killed in Iraq. Khan’s parents had denounced Trump during the Democratic National Convention.

Reince Priebus, chairman of the Republican National Committee, had urged Trump to stand behind Ryan and the senators for the sake of party unity. Some leading Republicans have expressed hope that Trump can at least stabilize his campaign by Labor Day, when many voters begin paying attention to congressional races.


But with such an erratic and belligerent candidate leading their ticket, many in the party have long seen a go-your-own-way strategy as inevitable.

David McIntosh, president of the Club for Growth, a group that advocates small government, said the organization was studying how to get Republican voters who may dislike Trump to turn out for the party’s down-ballot candidates. McIntosh said the Club for Growth intended to convince voters that they would need a “strong voice in the Senate and House,” regardless of their feelings about the presidential race.

“You hope Trump does well so that the base Republican vote comes out and is strong,” McIntosh said. “But you also have to plan for if he doesn’t do well.”

At the moment, that seems likely. Clinton opened a large lead last week in national polls, with a handful showing her leading by double digits. Perhaps more significantly, new surveys indicate that she has staked out leads in states Trump most likely needs to win the White House, including Florida, Pennsylvania, and Michigan, and that she is also close or edging ahead in Republican-leaning states such as Georgia, where at least one poll has her ahead.

Clinton’s advantage may ebb. The surveys were taken soon after the Democratic National Convention and during Trump’s gaffe-filled week. But Republicans are planning for the worst.