SCRANTON, Pa. — President Trump came to Joseph R. Biden Jr.’s hometown on Thursday and said he was prepared to run against the former Democratic vice president in November, changing gears after being “mentally” ready to take on Senator Bernie Sanders of Vermont.
“I was all set for Bernie, because I thought it was going to happen,” Mr. Trump said. “And then we had this crazy thing that happened on Tuesday.”
Mr. Trump, speaking at a televised town-hall-style event hosted by Fox News, was referring to Mr. Biden’s unexpected resurgence in the Democratic primaries on Tuesday, just as his campaign seemed at risk of collapsing.
In a venue where two different Trump supporters questioned whether the president’s slash-and-burn tone was necessary, Mr. Trump ridiculed Mr. Biden, 77, for a series of recent gaffes and repeated his insinuations that his rival’s mental acuity was slipping.
“There’s something going on there,” Mr. Trump said, to laughter from the crowd of a few hundred local supporters. The president referred to the votes “on Tuesday, which he thought was Thursday” — a reference to Mr. Biden’s use of the erroneous phrase “Super Thursday.”
The setting, in which Mr. Trump took questions from the audience, was an unusual one for the president, who regularly delivers hour-plus monologues before thousands at campaign rallies in large arenas. His appearance on Thursday was part of a series of events the network has staged with several Democratic candidates, including Mr. Sanders, who continues to battle Mr. Biden for the Democratic nomination.
Mr. Trump said he had prepared his attacks on Mr. Sanders. “So mentally, I’m all set for Bernie — communist, I had everything down, I was all set,” he said.
Mr. Trump narrowly carried Pennsylvania in 2016, by 44,000 votes.
Mr. Biden takes great pride in his roots in Scranton, a working-class city of 76,000 in northeastern Pennsylvania.
“Everything my sister Valerie and I learned was in Scranton,” he said during an appearance in October at the same venue, the Scranton Cultural Center. “Scranton creeps into your heart and never leaves you.”