Donald J. Trump’s unabashed and continuing hostility toward the parents of a slain Muslim American soldier, and his attacks on Republican leaders who have rebuked him for it, threaten to shatter his uneasy alliance with the Republican Party at the outset of the general election campaign.
Ignoring the pleas of his advisers and entreaties from party leaders in Washington, Mr. Trump only dug in further on Tuesday. He told a Virginia television station that he had no regrets about his clash with Khizr and Ghazala Khan, the parents of an Army captain killed in Iraq. And in an extraordinarily provocative interview with The Washington Post, Mr. Trump declined to endorse for re-election several Republicans who had criticized him, including the House speaker, Paul D. Ryan of Wisconsin, and Senator John McCain of Arizona, who both face primaries this month.
He also belittled Senator Kelly Ayotte of New Hampshire, who had criticized his treatment of the Khans, for not being supportive of his campaign.
For days, Mr. Trump’s top advisers and allies have urged him to move on from the feud, which erupted when Mr. Khan criticized him at the Democratic convention, and focus instead on the economy and the national security record of his Democratic opponent, Hillary Clinton. Yet, facing outcry on the left and right, Mr. Trump has insisted to associates that he has been treated unfairly by Mr. Khan, the news media and some Republicans, said people familiar with the campaign’s deliberations who insisted on anonymity to discuss them.
Republicans now say Mr. Trump’s obstinacy in addressing perhaps the gravest crisis of his campaign may trigger drastic defections within the party, and Republican lawmakers and strategists have begun to entertain abandoning him en masse.
Mrs. Clinton, who explicitly courted Republicans at last week’s convention, has already picked up a few telling Republican endorsements: Meg Whitman, the Hewlett Packard Enterprise executive who ran for governor of California as a Republican, backed Mrs. Clinton on Tuesday, as did Representative Richard Hanna of New York, a moderate Republican. Both denounced Mr. Trump’s treatment of the Khan family.
Still, the Trump campaign has left open the door to continued conflict with the Khan family. A memo circulated by Mr. Trump’s aides on Tuesday to his campaign surrogates urged them to express gratitude for the Khans’ sacrifice, but added that Mr. Trump had a “right to defend himself,” a person who received the document said.
In Mr. Trump’s five-day confrontation with a military family, Republicans have found the most agonizing test yet of their relationship with a candidate who has flouted political conventions around religion, race, gender and now military service. Republican strategists who once imagined Mr. Trump could be brought under control in a general election all but openly acknowledged this week that that prospect had vanished.
Mr. Trump’s advisers have impressed upon him for days that his clash with the Khans was counterproductive, urging him instead to show deference to them and train his attacks on Mrs. Clinton, people close to the campaign said. Emissaries from the Trump campaign who spoke with Republican lawmakers and party officials in Washington were given the same bracing assessment. A few Republicans in Washington even suggested that Mr. Trump should apologize to the Khans.
Mr. Trump has instead gone in the opposite direction, standing by his harsh treatment of the couple and brazenly antagonizing Washington Republicans.
Liesl Hickey, a Republican strategist who led the party’s defense of its majority in the House of Representatives in 2014, said lawmakers should feel liberated to split with Mr. Trump if their survival depended on it.
Ms. Hickey has quietly circulated a battle plan to Republican leaders and vulnerable members of Congress, calling for a sharpened focus on winning over wavering Republicans, moderates and women — even if that means withdrawing support from Mr. Trump.
“Even if you were with Trump before, it doesn’t mean that now you necessarily need to stay with him,” she said.
Ms. Hickey, who has worked extensively with Republicans in swing districts, said the urgent imperative for many of them was “getting away from the national message.” She added, “Everybody who hasn’t fully kicked off their campaigns yet should be encouraged to do this.”
The Republican Party has not yet come close to abandoning Mr. Trump’s candidacy: Most of the lawmakers who have denounced him for fighting with the Khans have not said they will vote against him in the general election.
Even the Republicans assailed by Mr. Trump on Tuesday responded in muted language. Zack Roday, a spokesman for Mr. Ryan, said Mr. Ryan had not sought Mr. Trump’s endorsement and was confident that he would win his primary. Ms. Ayotte, who faces re-election in November, wrote on Twitter that she would “always stand up for our military families and what’s best for the people of New Hampshire.”
Reince Priebus, the chairman of the Republican National Committee, has acknowledged the dispute with the Khans has harmed Mr. Trump, but he has pleaded with party leaders and donors to give Mr. Trump time to adjust to the general election, according to people briefed on Mr. Priebus’s conversations.
The Trump campaign has taken a few steps to recover its footing: Mr. Trump canceled a Thursday event in Plattsburgh, N.Y., a community with ties to the military in one of the country’s most heavily Democratic states. Trump strategists said the campaign would redouble its criticism of Mrs. Clinton’s support for military action in Iraq and Libya.
Paul Manafort, Mr. Trump’s top political adviser, accused Mrs. Clinton of seeking to “avoid a discussion of her failed record” at the State Department by pursuing Mr. Trump on other fronts.
“The Khan family has suffered an irreplaceable loss. For this loss, all Americans grieve,” Mr. Manafort said in an email. “The way to avoid these tragedies from continuing is to have leadership that will not make the mistakes of the Obama/Clinton administration.”
But already, Mr. Trump’s stubbornness has carried a heavy price: Senior party leaders have scolded him, including Mr. McCain, who castigated Mr. Trumpin a lengthy statement Monday.
Even one of Mr. Trump’s most steadfast allies, Gov. Chris Christie of New Jersey, said Tuesday that it was inappropriate to attack the Khan family.
“You’re not going to find me being critical of Mr. and Mrs. Khan no matter what,” Mr. Christie said. “It’s just inappropriate for us in this context to be criticizing them, and I’m not going to participate in that.”
Mr. Trump at first appeared on Tuesday to restrain himself, up to a point. At a campaign stop in Northern Virginia, he avoided mentioning the Khans by name, but continued to grumble about his treatment by the news media.
He lamented to supporters that reporters had overlooked the story of Patricia Smith, the mother of a serviceman killed in the attack in Benghazi, Libya, in order to highlight “other people” — apparently a reference to the Khan family.
“They give her virtually no airtime, and they give other people unbelievable amounts of airtime,” Mr. Trump said. “It’s just so unfair. It’s so unfair.”
By the end of the day, Mr. Trump had turned that grievance into an explosive confrontation with the leaders of his own party.