Joe Biden will 'address the nation' on election night, his campaign team have announced.

It's unusual for candidates to speak until enough results are in to either accept or concede the race.

Plans for a polling day speech are a sign of increasing concern that Donald Trump will claim victory before votes are counted.

US elections can take days or weeks to count and certify officially.

But TV news networks can usually call each state on the night through a combination of exit polls and early declarations.

Both will be hamstrung this year due to the huge spike in postal votes expected to arrive before - or in some states up to a week after - polls close.

Networks aren't expected to call the final result on the night this year - something which has angered the President.

Polls suggest Biden voters are dramatically more likely to vote early or by mail, and Trump voters are much more likely to vote on the day.

Experts have warned this could cause a "red mirage" where it appears Republicans have a lot more votes than they actually do.

And with Donald Trump's fondness for uninhibited social media outbursts, the Biden camp may be concerned that he will attempt to paint any change to the 'red mirage' as votes are counted as evidence of fraud.

The Biden campaign said the former Vice President would address the nation on Tuesday, and would be joined by wife Jill Biden, running mate Kamala Harris and her husband Doug Emhoff.

Biden, 77, campaigned in Michigan, home to the nation's car industry.

His former boss Barack Obama highlighted his administration's bailout of the auto sector after the 2008 financial crisis.

"Joe Biden and I - with the help of a Democratic Congress - rescued the auto industry," Obama told a Detroit rally.

Trump, 74, won both Pennsylvania and Michigan by narrow margins in his surprise 2016 victory. Reuters/Ipsos opinion polls show Biden leading Trump by 5 percentage points in Pennsylvania and 9 points in Michigan.