The president’s campaign manager, Bill Stepien, said Mr. Trump was “committed to debating Joe Biden regardless of last-minute rule changes.” But he also accused the commission of adopting the microphone rule to aid Mr. Biden, part of a days-long effort by the Trump campaign to undermine the integrity of the commission and to paint it as biased toward the Democratic candidate.
Earlier on Monday, Mr. Stepien — who mockingly referred to the nonpartisan commission as the “Biden Debate Commission” in a tweet — claimed that the commission had “promised” that the debate on Thursday would be about foreign policy and asked for it to discard the six subjects announced last week by the moderator, Ms. Welker. (The topics are the coronavirus, climate change, national security, leadership, “American families” and “race in America.”)
In fact, the debate organizers did not announce such a plan to focus on foreign policy, saying that the third debate would mirror the format of the first, with six subjects selected by the moderator. (It is true that in some campaign years, the third presidential debate has focused on foreign policy.)
A Biden spokesman, T.J. Ducklo, said on Monday that Mr. Stepien had sent the letter “because Donald Trump is afraid to face more questions about his disastrous Covid response,” adding: “The campaigns and the commission agreed months ago that the debate moderator would choose the topics.”
Mr. Stepien’s letter did not mention Mr. Trump’s baseless accusations that Ms. Welker, a respected White House correspondent, is biased. Mr. Trump’s aides, including a top adviser, Jason Miller, have previously spoken warmly about Ms. Welker, calling her “a very good choice” to oversee the debate.
The debate commission has had a tumultuous year. Its attempt to hold a virtual debate in Miami over coronavirus concerns prompted Mr. Trump to withdraw; that debate was eventually canceled, and the candidates held separate televised town hall events instead.
Alan Schroeder, an emeritus professor of journalism at Northeastern University who wrote a history of presidential debates, said on Monday that the microphone change “sounds good in theory, but I don’t see it as solving the problem.”