President Biden said on Friday that he would participate in a general-election debate with former President Donald J. Trump, a striking shift after months in which he and his campaign declined to commit to appearing onstage with his Republican rival.
Mr. Biden’s announcement, made in response to a question from the radio host Howard Stern, comes after pressure from television networks and Mr. Trump’s campaign for the president to agree to participate in debates.
When Mr. Stern asked Mr. Biden if he would debate Mr. Trump, the president replied: “I am, somewhere, I don’t know when, but I am happy to debate him.”
Mr. Biden’s remarks appeared to be off the cuff, rather than a planned announcement of a shift in his campaign’s strategy, according to a top Democratic official familiar with its thinking. The Biden campaign directed questions on Friday about whether its stance on debates had changed to Mr. Biden’s comments on the Stern program.
A top campaign adviser to Mr. Trump, Chris LaCivita, replied to the Biden comments by writing on social media: “Ok let’s set it up !”
Mr. Biden and Mr. Trump debated twice in 2020, with Mr. Trump pulling out of a third debate after testing positive for the coronavirus because he refused to participate virtually. Ill will remains on the Biden side out of a widespread belief that Mr. Trump knowingly exposed Mr. Biden to the virus during the first debate, which the former president has denied.
This month, the five major TV news networks and The Associated Press wrote an unusual letter to the Biden and Trump campaigns urging them to debate. Some of Mr. Biden’s top aides and closest advisers have been longtime critics of the presidential debate system, which is organized by the nonpartisan Commission on Presidential Debates.
In November, the debates commission announced that three presidential debates would take place in San Marcos, Texas; Petersburg, Va.; and Salt Lake City. A vice-presidential debate is to be held in Easton, Pa.
This month, the Trump campaign sent a letter asking the debates commission to move its three planned debates earlier in the fall and to add more to the schedule.
Over the last month, Mr. Trump has tried to ratchet up the pressure on Mr. Biden to debate, with two of his top advisers, Susie Wiles and Mr. LaCivita, strategizing on how best to do so.
At Mr. Trump’s recent rallies, he has goaded Mr. Biden over debates: Before the former president takes the stage, screens show an image of his Truth Social post claiming his willingness to debate Mr. Biden “anytime, anywhere, anyplace.”
A staff member then brings an empty lectern on the stage, with a sign bearing those three words. The lectern remains in place while Mr. Trump gives his campaign speech.
“See the podium?” Mr. Trump said at a rally this month in Schnecksville, Pa. “I’m calling on crooked Joe Biden to debate anytime, anywhere, any place.”
The Trump campaign has also issued other public challenges to Mr. Biden, saying in interviews, on social media and in printed campaign material that Mr. Trump will debate Mr. Biden anytime and anywhere. Mr. Trump, who did not participate in any Republican primary debates, has even said he is ready to confront Mr. Biden onstage now — months earlier than debates typically begin.
Mr. LaCivita has indicated that the campaign wants more debates than the traditional three — believing that the more the American public is exposed to Mr. Biden, the less confident it will be in his capacities to lead.
Still, Mr. Trump’s eagerness could backfire. In the 2020 campaign, he underestimated Mr. Biden’s ability, and the debates — especially the first one, in which his ranting frequently interrupted his rival — were widely believed to have hurt Mr. Trump.
Part of the problem was that Trump and his allies have largely experienced Mr. Biden through the conservative news media, where they often see a mash-up of the most unflattering clips of Mr. Biden stumbling, looking lost or otherwise showing his age.
The impression among many Trump advisers is that they are dealing with a president who is barely able to complete a sentence. Mr. Trump was so surprised by Mr. Biden’s energetic performance at his recent State of the Union address that he speculated without any evidence that the president must have been on drugs.
Michael Gold contributed reporting.