US Election: Donald Trump and Joe Biden clash during final debate

The final US presidential debate on Friday saw organisers introduce a very powerful tool between Republican candidate Donald Trump and Democratic contender Joe Biden - a mute button.

The candidate's microphones were muted during each other's 2-minute opening remarks to ensure no interruptions.

"The debate commission will turn on their microphone only when it is their turn to answer," debate host Kristen Welker said.

Viewers wondered whether the mute button was even working until the end of Donald Trump's two-minute speaking time allowance on healthcare. 

"… And we're going to do even better on… [goes silent]."

On the whole, the American public heard a more informative, policy focussed debate on topics such as the coronavirus.

"Anyone who is responsible for that many deaths should not remain as the President of the United States," Biden said. 

Another topic - International affairs - particularly Donald Trump's relationship with North Korean dictator Kim Jong Un. 

"Having a good relationship with the leaders of other countries is a good thing. We had a good relationship with Hitler before he invaded Europe," Trump said.

Closer to home, they spoke of race relations.

"I can't even see the audience because it's so dark but I don't care who's in the audience because I'm the least racist person in this room," Trump said.

"[Trump] started off his campaign saying he was going to get rid of 'those Mexican rapists'. He has banned Muslims… c'mon this guy has a dog whistle about as big as a fog horn," Biden said.

And they couldn't resist trading barbs against each other's personal affairs - where their money came from - or has gone.

"I have not taken a penny from any foreign source," Biden said, after Trump accused him of taking money from Russia.

CNN's analysis afterwards claimed Donald Trump spoke for just over three minutes more than Biden, but he was generally more reserved than he's been in previous debates. 

He has just 12 days to attempt to win over swing voters and they're reducing by the day.