President Trump, in an extraordinary break from the norms of modern campaigning, said on Thursday that he would refuse to participate in the next presidential debate after organizers changed the event to a virtual format because of health concerns about the coronavirus.
His withdrawal from the Oct. 15 event came shortly after the Commission on Presidential Debates, citing the “health and safety of all involved,” abandoned plans to stage the next in-person debate in Miami, saying that Mr. Trump and Joseph R. Biden Jr. would instead participate remotely from separate locations.
But Mr. Trump, whose recent contraction of the coronavirus was a significant impetus for the commission to modify its plans, immediately dismissed the idea of a remote debate as “ridiculous” and accused the debate commission without evidence of seeking to protect his Democratic opponent.
“No, I’m not going to waste my time on a virtual debate,” Mr. Trump told the Fox Business anchor Maria Bartiromo in a television interview. “That’s not what debating is all about. You sit behind a computer and do a debate — it’s ridiculous.”
“That’s not acceptable to us,” Mr. Trump added.
The debate commission decided to change to a virtual format after members of its production team objected to the safety risks of staging another in-person event at an indoor venue, according to a person familiar with its deliberations.
Mr. Trump’s defiance may pose the most significant test to the debate commission’s legitimacy since the group was founded in 1987. There is no law that presidential candidates must debate. Traditions and norms govern the practice, and like many political institutions in recent years, the commission’s board now faces its own Trumpian stress test.
The debate commission was already under pressure to reform its safety protocols after the first debate last week in Cleveland, where Mr. Trump’s family members and aides declined to wear masks in the debate hall, flouting regulations set by the organizers. Mr. Biden’s aides had also expressed concern about their candidate’s potential exposure next week to a president who could still be infectious.
Mr. Biden’s team said on Thursday that he would agree to the virtual format. “Vice President Biden looks forward to speaking directly to the American people,” said Kate Bedingfield, a deputy campaign manager.
But Mr. Trump’s campaign manager, Bill Stepien, issued a blistering attack on the debate commission, calling its members “swamp monsters” and describing the move to a virtual debate as “pathetic.”
“The safety of all involved can easily be achieved without canceling a chance for voters to see both candidates go head-to-head,” Mr. Stepien said in a statement. “We’ll pass on this sad excuse to bail out Joe Biden and do a rally instead.” He also claimed that Mr. Trump “will have posted multiple negative tests prior to the debate,” although White House officials have repeatedly declined to give details about Mr. Trump’s current health status and the president has not yet tested negative for the virus.
Mr. Trump, in the Fox Business interview, said he learned of the change to a virtual format on Thursday, and senior Trump campaign officials insisted that they had not been consulted about the decision ahead of the commission’s morning announcement. But there were indications that people in the president’s circle were aware on Wednesday of the debate commission’s thinking about a virtual debate.
The president also sought repeatedly to undermine the integrity of the debate commission. He accused the moderator of the next debate, Steve Scully of C-SPAN, of being a “never Trumper,” without offering evidence for his claim. He said the moderator of the first debate, Chris Wallace of Fox News, “was a disaster” who favored Mr. Biden. And he said the commission’s plan for a remote debate was about “trying to protect Biden.”
In fact, a presidential debate with candidates in different locations is not unprecedented.
In 1960, the third debate between John F. Kennedy and Richard M. Nixon was held remotely. Kennedy debated from a television studio in New York; Nixon appeared from Los Angeles.
A split-screen camera feed allowed viewers to watch both candidates simultaneously, with the men filmed on a pair of identical sets. The moderator of that debate, Bill Shadel of ABC News, conducted the proceedings from a third studio in Chicago.
How to safely stage a pair of indoor, in-person debates between Mr. Biden and Mr. Trump, who tested positive for the coronavirus last week and spent three days at the Walter Reed National Military Medical Center, has been the subject of intense conversations among board members of the debate commission in recent days.
Aides to Mr. Trump had privately discussed the notion of debates held outdoors, but people familiar with the commission’s deliberations said the Trump campaign had never formally proposed that idea.
Organizers said the moderator, Mr. Scully, would still conduct the proceedings from Miami at the Adrienne Arsht Center for the Performing Arts. The debate is to be held in a town-hall-style format with questions from South Florida voters, who would also be present at the venue.
Both candidates have previously said they planned to participate in the Miami debate, with Mr. Trump insisting that he is “looking forward” to attending the event, despite the uncertainty over his health.
Mr. Biden has said he is deferring to the debate commission and its health adviser, the Cleveland Clinic, to ensure a safe physical environment for the audience and participants.
“If he still has Covid, we shouldn’t have a debate,” Mr. Biden told reporters on Tuesday night after a speech in Gettysburg, Pa. “I will be guided by the guidelines of the Cleveland Clinic and what the docs say is the right thing to do.” His aides have said the onus is on Mr. Trump to demonstrate that he would not be contagious onstage.
The debate commission did not address the third debate in its statement on Thursday. That matchup is scheduled to be held at Belmont University in Nashville on Oct. 22, with Kristen Welker of NBC News as the moderator.
The vice-presidential debate took place as planned on Wednesday in Salt Lake City, with Senator Kamala Harris of California and Vice President Mike Pence debating in person — albeit with plexiglass dividers between them.
Patricia Mazzei contributed reporting.