Former President Donald J. Trump said on Tuesday that he would “absolutely” be willing to debate Vice President Kamala Harris, who has already clinched commitments from enough delegates to become the Democratic presidential nominee.

“I would be willing to do more than one debate, actually,” he said.

In a call with reporters hosted by the Republican National Committee, however, he also said he was “not thrilled” about having a debate hosted by ABC — even though he and President Biden agreed months ago to take part in a debate put on by that network in September.

Mr. Trump’s remarks were his first extensive comments on Ms. Harris since Mr. Biden announced he would drop out of the presidential race on Sunday. It was the second time this week he appeared to try to change the terms of a debate.

On Sunday, after Mr. Biden declared he would end his bid, Mr. Trump posted on Truth Social that the debate that had been scheduled for September should be moved to Fox News, a channel on which he generally gets more favorable coverage, from ABC.

During Tuesday’s call, Mr. Trump — who for months insisted he would debate Mr. Biden anytime and anywhere — told reporters that the debate terms he agreed to applied only with Mr. Biden.

“I haven’t agreed to anything. I agreed to debate with Joe Biden,” Mr. Trump said. “But I want to debate her, and she’ll be no different because they have the same policies.”