Washington DC - Donald Trump ruled out a second US presidential debate with rival Kamala Harris on Wednesday, hours after Fox News offered to host a candidate showdown later this month before election day on November 5.

The Republican ex-president and Democratic vice president, locked in an excruciatingly close White House battle, have faced off just once, in September, and despite suggestions by multiple news outlets, it appears they will not meet again before the vote.

"It is very late in the process, [early] voting has already begun – there will be no rematch!" Trump said in an all-caps post on his Truth Social media platform, nixing the possibility of a follow-up to the candidates' first debate in Philadelphia.

"Kamala stated clearly, yesterday, that she would not do anything different than Joe Biden, so there is nothing to debate," Trump added.

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Harris had previously challenged Trump to a debate hosted by CNN on October 23, but the former president declined.

Trump also said that Harris, who became the Democratic nominee after President Biden ended his re-election bid following his disastrous debate with Trump, had backed out of a previous debate offered by Fox, although the Harris campaign had not publicly accepted the proposal.

The candidates did agree to debate on ABC News on September 10, and the vice presidential running mates – Republican JD Vance and Democrat Tim Walz – squared off on October 1.

But while Trump said he had agreed to participate in a September 4 debate on Fox, as well as one on September 25 on NBC News, Harris never did.

The vice president, after positive reviews that she had bested Trump in their encounter, had expressed interest in doing a second debate, but the plans never came to fruition.

Fox, for its part, sent letters Wednesday to the two campaigns offering "one final pitch for a debate" between Harris and Trump, either on October 24 or October 27.

"This would present an opportunity for each candidate to make his or her closing arguments," wrote Jay Wallace, president of Fox News Media.