Priebus was saying in effect that it would be possible to build a wall around Donald Trump and not have the G.O.P. pay for it. Trump did not define its values in the long term, even if he might temporarily defile them. “We’re the party of the ‘open door,’ ” Priebus told me, as he often does. Not big, beautiful walls.

For a while this spring, it seemed possible to contain the earthquake. Trump showed flickering signs of “maturing” as a candidate, and Republicans seemed willing to “support the nominee,” if not endorse him. The “normalization” of Donald Trump became a media watchword, the idea that his daily affronts could be integrated into the routine paces of a quadrennial exercise. Formerly hostile primary opponents like Marco Rubio, Lindsey Graham, Bobby Jindal and Rick Perry all at various points said they would support Trump or were at least no longer (in Rubio’s case) deriding him as a “fraud,” “con man” and “lunatic” or (in Graham’s) a “race-baiting, xenophobic, religious bigot” or (in Jindal’s) a “madman who must be stopped” or (in Perry’s) a “barking carnival act.” I imagined Trump laughing at how easy it was to get Republicans to submit to him after he had savaged so many of them during the primaries. Actually there was no need to imagine because Trump was doing exactly that. “I’ve never seen people able to pivot like politicians,” he said at a rally in California in late May while boasting of his support from Perry. In an interview, I asked Trump if it was harder to flip politicians or the real estate people he has dealt with over the years. His smirk was audible over the phone. “Well, I’m not referring to any politicians in particular, but I’ve said many times that businesspeople are much tougher,” Trump said. “Politicians tend to be much more deceptive and deceiving and more willing to break a deal. But they are not as tough.”

Priebus, meanwhile, kept working the phones, trying to coax anti-Trump Republicans back to the party line and persuade — beg — Trump to lay off the elected Republicans he kept dumping on. “I have encouraged him to constantly offer grace to people that he doesn’t think are deserving of grace,” Priebus said. Trump, in turn, calls Priebus “Mr. Switzerland” and speaks well of him. “Reince is a peacemaker, a very good person for getting people together,” he said. Trump was calling me from his limo after a rally in Anaheim, Calif. He was in the midst of an intrapartisan grudge tour of the American West, during which he disparaged, among other Republicans, Jeb Bush, the South Carolina governor, Nikki Haley, and the New Mexico governor, Susana Martinez, who is one of the highest-profile Hispanic elected officials in the G.O.P. He also reiterated that Romney was a “loser” and a “choker” and for good measure boasted that “I have a store that’s worth more money than he is.”

Priebus’s mother is Greek, which he says trains him for dealing with whatever the Greek word for mishegas is. “Ever see ‘My Big Fat Greek Wedding’?” he asked. “That’s my family, that’s my life. The arguing starts at 7:30 in the morning, everyone’s in each other’s business. It was good family chaos.” I asked if what the G.O.P. was going through now was “good family chaos.”

“It depends how it turns out,” he said.

At this point in the pre-general-election calendar four and eight years ago, Romney and John McCain had built massive campaign operations and fund-raising networks that were orders of magnitude larger than Trump’s. They had accumulated armies of elected officials promoting them and were diligently making peace with vanquished opponents and paying courtesy calls to party dignitaries and congressional leaders in the name of “unity.” The period between the end of the primaries and the start of the conventions is typically one of consolidation, good-will harvesting and turning full attention to the general-election opponent — all of which Trump has succeeded in achieving the 180-degree opposite of.

Trump would of course be the first to point out that both McCain and Romney lost and that he has been doubted at every step of his campaign. But the degree to which he seems unconcerned with his pariah status among name Republicans remains a key feature of his pursuit. To a comical extent, top Republicans willed themselves invisible when I reached out to them for this article, fearing, not incorrectly, that the conversation would turn to Trump. This included some of the most typically quotable Republicans, including former Trump challengers like Graham (“He’s sorta had his fill talking about Trump,” a spokesman emailed), Perry (“Thanks for thinking of him”) and Ted Cruz (“Not great timing on our end”); the previous nominee Mitt Romney (“You are kind to think of me,” he wrote); Trump stalwarts like Chris Christie (“We are going to take a pass this time”); Trump-averse Republican governors like Charlie Baker of Massachusetts (“The governor won’t be available”); and senators like Mike Lee, of Utah (“Senator Lee would love to talk to you about the state of the G.O.P. and conservatism in general. We are free anytime after Nov 8.”).