"We're going to win this race," Mr Biden told supporters in Wilmington, Delaware, on Friday night, striking a confident tone. He was joined by his running mate, California Senator Kamala Harris. He said he was on track to win more than 300 Electoral College votes and pointed out that more people had voted for his campaign - over 74 million people - than any US presidential candidate in history.

Mr Biden said Americans had given him a mandate to tackle the coronavirus pandemic, the struggling economy, climate change and systemic racism.

On Friday for the third straight day the US set a fresh record for new Covid-19 cases, with more than 127,000 infections.

Appealing for national unity, he said: "We must put the anger — and the demonisation — behind us. It’s time for us to come together as a nation and heal.”