President Trump is closing in on crucial Catholic support after his appearance at the 79th Alfred E. Smith Memorial Foundation Dinner. With a speech poking fun at himself and opponents, he can boast of standing with them at their signature event and point to Vice President Harris’s video message landing with a thud.

On Tuesday’s “Conversation with Cardinal Dolan Podcast,” the archbishop of New York, Timothy Cardinal Dolan, said he was “upset” that Ms. Harris was a no-show at New York City. “It’s a shame,” he said, “because the nature of the evening is to bring people together” in “civility, patriotism, humor.” He added that the event “is not a campaign speech” or “campaign stop.”

The political implications of the dinner, however, are clear. It’s a chance for presidential candidates to shelve differences and unite under the banner of, in Al Smith, a governor of New York who in 1928 became the first Catholic candidate for president. “The American people never carry an umbrella,” he said, capturing the spirit of the night. “They prepare to walk in eternal sunshine.”

This year, Ms. Harris chose to rain on the parade. The evening’s comic emcee, Jim Gaffigan, joked that she had time for other appearances including “the long-time staple of campaigning: ‘The Call Her Daddy Podcast.’” These quips felt a little uncomfortable since the vice president wasn’t there to laugh along as Trump did when he was the punchline.

Rather than a speech, Ms. Harris performed a skit with the former “Saturday Night Live” actress Molly Shannon, 60, dressed in a Catholic schoolgirl outfit. Revulsion was audible when she did her bit about smelling her armpits, and she took up about as much time singing Ms. Harris’s praises for being a woman as the candidate did addressing the group.

“I don’t even know what that noise you’re making is,” Mr. Gaffigan said after the video concluded. Is there a name for a mixture of groans, boos, and an uncomfortable applause? Ms. Harris offered political barbs rather than jokes and none of the self-deprecating deadpan which, Trump said, Cardinal Dolan had reminded him is a requirement.

In contrast, Trump made sport of his ego, joking that he couldn’t name a single flaw. “I guess I just don’t see the point of taking shots at myself,” he said, “when other people have been shooting at me.” Regardless, he said, it was “a pleasure to be anywhere in New York without a subpoena.”

Trump made common cause with Mayor Adams of New York over being pursued by the Justice Department, he said, for criticizing President Biden over the border. However, now that the president is no longer in the race, Trump said he likes him “quite a bit” and will like Ms. Harris “quite a lot” once the race ends, no matter who prevails.

Trump praised many Democratic officeholders in attendance, patting the Senate majority leader, Senator Schumer, on the shoulder several times, and saying he had written “his first check” when the legislator ran for office. Although a previous Gotham leader, Mayor Bloomberg, sat while everyone else stood and glowered without ever applauding, he fell short of Trump’s snark.

Only Mr. Adams’s predecessor, Mayor De Blasio, drew Trump’s ire. He teased Mr. de Blasio as “terrible” for the city and — with a grin that seemed mindful of Woody Allen’s rule, “If it bends, it’s funny. If it breaks, it’s not funny,” — said, “I don’t give a shit if this is comedy or what.” This breach of decorum was allowed to pass as humor, demonstrating the goodwill he’d accumulated.

Trump called Ms. Harris’s failure to attend “deeply disrespectful,” saying it was too bad because “we can’t get enough of hearing her beautiful laugh.” In a pitch-perfect read of the audience, he said his opponent was “in Michigan receiving communion from Gretchen Whitmer,” the governor who was forced to apologize after pantomiming the Catholic sacrament with a Dorito.

“You have to go to the dinner,” Trump said, pointing skyward, “or bad things are going to be done to you from up there.” He reminded the audience that the last candidate to skip the event, Vice President Mondale in 1984, lost 49 states to President Reagan. This was proof, the former president said, “there is a God, if you’re questioning it.”

Trump said the assassination attempts had renewed his faith. “I have a very fresh appreciation,” he said, “for how blessed we are by God’s providence and His divine mercy.” It was a side the former president doesn’t show often, which is to the detriment of his campaign.

Yet asking Trump to stick to a script is, as a former TV producer remarked to me, like “asking Jimmy Hendrix to play the National Anthem straight.” On this night, although the former president was denied a teleprompter — which, he pointed out, Mr. Gaffigan was allowed to use — the former president was back home and back in his element, cracking wise and shrugging off insults.

Cardinal Dolan does not offer an endorsement, but he thanked Trump for attending while omitting mention of Ms. Harris’s contribution. If Catholic voters prove the difference in key states like Pennsylvania, the vice president may regret not basking in the night’s bipartisan sunshine — and find it not at all funny that this was the night that broke her campaign.