Donald Trump and Joe Biden will have their microphones muted for parts of their final debate tomorrow to allow each candidate a block of uninterrupted time to speak and avoid the rancour of the two candidates' first encounter. 

For this week's 90-minute debate, the organisers will give each candidate two minutes of uninterrupted time at the beginning of each 15-minute segment of the debate. NBC News correspondent Kristen Welker will moderate.

Trump objected to the change, but said he would still take part.

"I will participate but it's very unfair that they changed the topics and it's very unfair again that we have an anchor who's totally biased," he claimed.

Family issues, climate change and race have been proposed as topics, but Trump's camp said it should include foreign policy.