As the clock neared 2am on the US East Coast (6pm AEDT), Trump had been projected to win the two crucial swing state of North Carolina and Georgia.
He also held narrow leads in fellow battlegrounds Wisconsin, Michigan, Arizona, Nevada and, crucially, Pennsylvania.
North Carolina was the first swing state to be called, and shortly afterwards Georgia fell the same way – the first state to change hands this election after Joe Biden took it in 2020.
Still, neither candidate has reached the 270 Electoral College votes required to win the election.
A similar scenario had played out in 2020, when Trump appeared set for victory only for postal ballots and other votes counted late on to overwhelmingly favour Biden and send him to the White House.
The Harris campaign believes the race will become clearer in the coming hours: after midnight in Michigan, when a large number of blue votes are expected, and between about 7pm and 9pm AEDT in Wisconsin, while the Philadelphia count still has a long time left.
Winning those three states – the so-called “Blue Wall” – would be enough to keep the Democrats in the White House, assuming the rest of the non-battleground states go as expected.
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With Trump having won North Carolina and looking strong in Georgia, it appears the only viable path to victory for Harris.
But winning Pennsylvania would now be enough to hand Trump victory, and the Republican candidate held a buffer of 3 per cent with 96 per cent of the vote in the Keystone State counted.
Kamala Harris’s campaign chair Jennifer O’Malley Dillon said they still see a potential election win through the Blue Wall, and that crucial counting will continue overnight and into Wednesday, local time.
“We have known all along that our clearest path to 270 electoral votes lies through the Blue Wall states,” O’Malley Dillon said, adding that “we’ve been saying for weeks that this race might not be called tonight”.
“Those of you who were around in 2020 know this well: it takes time for all the votes to be counted – and all the votes will be counted.”
Harris’ campaign said the current vice president will not give a speech tonight.
In addition to claiming North Carolina and holding an edge in the swing states, Trump also held a lead in the popular vote of about 5 million – albeit with many votes from the Democratic stronghold of California still to be counted.
No Republican has won the popular vote since George W Bush in 2004.