Democrat Joe Biden narrowly overtook President Donald Trump in the vote counts in Georgia and Pennsylvania, with the presidency hinging on the outcome of tight contests in key battleground states.
Neither candidate has reached the 270 Electoral College votes needed to win the White House, though Mr Biden has the advantage after eclipsing Mr Trump in Wisconsin and Michigan, two crucial Midwestern battleground states.
That left both campaigns increasingly focused on developments in Pennsylvania and Georgia, where Mr Biden had an advantage of more than 900 votes on yesterday morning.
He has now moved ahead of the incumbent president in Pennsylvania although the race is still too close to call.
Officials in Georgia confirmed that a recount would be held because of the close margin in the state.
It could take several more days for the vote count to conclude in some states, allowing a clear winner to emerge.
With millions of ballots yet to be tabulated, Mr Biden has already received more than 73 million votes nationally, the most in history.
As Americans entered the third full day after the election without knowing who won the race, anxiety about the outcome was building.
With his pathway to re-election appearing to narrow, Mr Trump was testing how far he could go in using the trappings of presidential power to undermine confidence in the vote.
He has been spending yesterday at the White House tweeting, watching results come in and continuing to cast unfounded doubt over the integrity of the election.
He said in a statement released by his campaign: “We believe the American people deserve to have full transparency into all vote counting and election certification.”
He added: “This is no longer about any single election. This is about the integrity of our entire election process.”
He threatened continued legal action, saying: “We will pursue this process through every aspect of the law to guarantee that the American people have confidence in our government.”
On Thursday, Mr Trump advanced unsupported accusations of voter fraud to falsely argue that his rival was trying to seize power in an extraordinary effort by a sitting American president to sow doubt about the democratic process.
“This is a case when they are trying to steal an election, they are trying to rig an election,” Mr Trump said from the podium of the White House briefing room.
Mr Biden spent Thursday trying to ease tensions and project a more traditional image of presidential leadership.
After participating in a coronavirus briefing, he declared that “each ballot must be counted”.
“I ask everyone to stay calm. The process is working,” Mr Biden said.
“It is the will of the voters.
“No-one, not anyone else who chooses the president of the United States of America.”
Mr Trump showed no sign of giving up and was back on Twitter, insisting the “US Supreme Court should decide!”
Mr Trump’s campaign engaged in a flurry of legal activity to try to improve the Republican president’s chances, saying it would seek a recount in Wisconsin and filing lawsuits in Pennsylvania, Michigan and Georgia.
Judges in Georgia and Michigan quickly dismissed Trump campaign lawsuits there on Thursday, when Mr Trump still held a small edge in Georgia - though Mr Biden was gaining on him as votes continued to be counted.
The same was true in Pennsylvania, where Mr Trump’s lead slipped and the former vice president moved ahead.
One reason is that elections officials were not allowed to process mail-in ballots until election day under state law.
It is a form of voting that has skewed heavily in Mr Biden’s favour after Mr Trump spent months claiming without proof that voting by mail would lead to widespread voter fraud.
Mail ballots from across the state were overwhelmingly breaking in Mr Biden’s direction.
A final vote total may not be clear for days because the use of mail-in ballots, which take more time to process, has surged as a result of the coronavirus pandemic.
