Kamala Harris accuses Trump of ‘backpedaling’ on presidential debate

Kamala Harris has accused Donald Trump of “backpedaling” from a previously agreed presidential debate in September, as the Trump campaign said that it would not agree to finalizing plans until Harris formally becomes the Democratic nominee.

Harris told reporters on Thursday that she was “ready to debate Donald Trump”. A debate, hosted by ABC News, was planned for 10 September.

Related: Vast majority of Black voters trust Harris and distrust Trump, survey finds

“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 debate was one of two debates that Joe Biden and Trump had agreed on. The first one was hosted by CNN on 27 June, during which Biden delivered a disastrous performance that revived concerns he was too old for a second term and ultimately accelerated his decision to stand down as the Democratic candidate.

Biden dropped out of the race and endorsed Harris as his successor, and Democrats have since rallied around her. This week the vice-president earned enough delegate support to make her the nominee, but is not set to formally accept the nomination until the Democratic national convention in mid-August.

“General election debate details cannot be finalized until Democrats formally decide on their nominee,” said Steven Cheung, the Trump campaign communications director, in a statement late on Thursday.

“It would be inappropriate to schedule things with Harris because Democrats very well could still change their minds.”

Trump has said he would prefer to shift the debate to Fox News, but he would be willing to face off with Harris more than once.

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. Biden halting performance caused his support within the Democratic party crumbled, and he ended his re-election bid on Sunday.