Vice president Kamala Harris has told reporters that she is “ready to debate Donald Trump”.
She accused him of “back-pedalling” away from a previous agreement for a debate hosted by ABC News on September 10.
“I think the voters deserve to see the split screen that exists in this race on the debate stage,” she said after landing at Joint Base Andrews following a trip to Indiana and Texas.
The September 10 debate was one of two debates that President Joe Biden and Mr Trump had agreed on.
The first one was hosted by CNN on June 27, but Mr Biden has since dropped out of the race and endorsed Ms Harris as his successor.
Mr Trump has said he would prefer to shift the debate to Fox News, but he would be willing to face off with Ms Harris more than once.
Ms Harris did not respond to a question about having Fox News host a debate.
Alex Conant, a Republican consultant, said the debate could be “decisive”.
“It’s the only time voters really tune in,” he said.
This year’s campaign has already shown the potential power of a debate.
Mr Biden’s disastrous performance on June 27 revived concerns that he was too old for a second term.
His support within the Democratic Party crumbled, and he ended his re-election bid on Sunday.
