US President Donald Trump has criticised plans by the debates commission to mute candidates' microphones during portions of the final presidential debate.
The Commission on Presidential Debates announced late on Monday that Trump and his Democratic rival Joe Biden will each have two minutes of uninterrupted time to initially answer the moderator's questions when they face off on Thursday.
Organisers hope the rule change will prevent the debate from descending into chaos and frequent interruptions, as the first debate did last month.
"The whole thing is crazy," Trump said in a phone interview on Fox News, saying the commission had already unfairly muted his microphone during debates in 2016.
"I just think it's very unfair," Trump told reporters aboard Air Force One as he returned from Arizona on Monday evening.
"I will participate, but it's very unfair that they changed the topics and it's very unfair that, again, we have an anchor who's totally biased."
The match-up is scheduled for Thursday in Tennessee, less than two weeks before the November 3 election and as Trump is trailing Biden in the polls.
Trump shunned formal debate practise on Tuesday and was instead heading for another of his big rallies.
Biden took the opposite approach, holing up for debate prep.
Australian Associated Press