Former President Donald J. Trump, in a social media post on Sunday night, questioned his agreement to debate Vice President Kamala Harris next month.
Mr. Trump had agreed months ago to a debate with President Biden on Sept. 10 on ABC News. After Mr. Biden ended his campaign and Ms. Harris replaced him as the Democratic nominee, Mr. Trump wavered, trying to get Ms. Harris to agree to debate on Fox News instead, but he ultimately agreed to honor the original plan.
On Sunday, though, he complained about what he called a “ridiculous and biased interview” of Senator Tom Cotton, Republican of Arkansas, by the ABC News reporter Jonathan Karl, and about ABC’s “so-called Panel of Trump Haters.”
“I ask, why would I do the Debate against Kamala Harris on that network?” he wrote.
He continued, misspelling the name of the Democratic strategist Donna Brazile and using a disparaging nickname for the news anchor George Stephanopoulos: “Will panelist Donna Brazil give the questions to the Marxist Candidate like she did for Crooked Hillary Clinton? Will Kamala’s best friend, who heads up ABC, do likewise. Where is Liddle’ George Slopadopolus hanging out now? Will he be involved. They’ve got a lot of questions to answer!!! Why did Harris turn down Fox, NBC, CBS, and even CNN? Stay tuned!!!”
The debate between Mr. Trump and Mr. Biden in June was on CNN.
The candidates’ tussling over the dates, venues and formats of debates has been almost as contentious this year as the first debate was.
For decades, the forums have been organized in a standardized manner by the nonpartisan Commission on Presidential Debates. But this year, the commission was sidelined when Mr. Biden and Mr. Trump agreed to negotiate directly with television networks, and to hold the events earlier than the commission had. They agreed to a debate on CNN on June 27, and a debate on ABC News on Sept. 10.
Early this month, Mr. Trump dropped out of the ABC News debate and tried to persuade Ms. Harris to appear on Fox News. When she did not, he reversed himself a few days later and agreed to attend the ABC debate after all.
Now, Ms. Harris’s campaign is calling for a change to the original rules for that debate. Mr. Biden had asked for each candidate’s microphone to be muted when it wasn’t his turn to speak, and Mr. Trump agreed.
“We have told ABC and other networks seeking to host a possible October debate that we believe both candidates’ mics should be live throughout the full broadcast,” Brian Fallon, a spokesman for the Harris campaign, said in a statement, referring to the scheduled Sept. 10 debate and to an additional debate in October that the campaign has said it is open to negotiating. “Our understanding is that Trump’s handlers prefer the muted microphone because they don’t think their candidate can act presidential for 90 minutes on his own.”
Mr. Trump’s campaign responded by noting that it was Mr. Biden who requested the muted mics to begin with.
“ABC offered the exact same debate rules as CNN, and we accepted — as did the Harris camp,” a Trump spokesman, Jason Miller, said. “Now, after the Harris campaign has begun debate prep, they’re clearly concerned about what they’re seeing from Harris’ performance and want a whole host of rules changes.”
Mr. Trump’s social media post on Sunday — with its complaints about Ms. Brazile and Mr. Stephanopoulos — suggested that it was unclear who would moderate the debate, but that is not true. The ABC News anchors David Muir and Linsey Davis have been named as the moderators.
Michael Gold and Jonathan Swan contributed reporting.