It's postal ballots that might carry the day for Joe Biden.

Veteran Republican pollster Whit Ayres told Mike Hosking massive numbers of Democrats voted by mail.

He says mail ballots remain to be counted - and in places like Philadelphia they're going three to one to Joe Biden.

A confident Biden says the Democrats remain on track to claim the White House, telling America: "We believe we will be the winners."

Biden has just spoken to the nation and said: "After a long night of counting it's clear we're winning enough states to win 270 votes to win the presidency."

He and deputy Kamala Harris were on track to win more votes than any other ticket in history.

Earlier today Biden took another step towards the White House, with pundits predicting he will win the key state of Wisconsin - and with it 10 crucial electoral votes.

Meanwhile Donald Trump has stepped up legal threats over several remaining states - with lawyers heading to court to halt the vote counting in Michigan. They claim they have been denied "meaningful access" to observe the counting in the state, which contributes 16 votes to the Electoral College.

His campaign team is also seeking to stop the ballot counting in Pennsylvania - even though they are claiming victory in the state with 84 per cent of votes tallied.

The latest results have Biden with 248 votes compared to Trump's 214. The winner requires 270 votes.