Democrat Joe Biden stood on the cusp of winning the presidency on Friday night, as the long work of counting votes widened his lead over Donald Trump in critical battleground states.
High turnout, a huge number of mail-in ballots and slim margins between the two candidates all contributed to the delay in naming a winner.
But Mr Biden held leads in Pennsylvania, Nevada and Georgia, putting him in an ever-stronger position to capture the 270 Electoral College votes needed to take the White House.
Mr Trump stayed in the White House and out of sight, as more results trickled in and expanded Mr Biden’s lead in must-win Pennsylvania.
His opponent addressed the nation on Friday night near his home in Wilmington, Delaware, and acknowledged the sluggish pace of the count “can be numbing”.
“Never forget the tallies aren’t just numbers: They represent votes and voters.”
He expressed confidence that victory ultimately would be his, saying: “The numbers tell us a clear and convincing story: We’re going to win this race.”
Standing alongside his running mate, Senator Kamala Harris, and against a backdrop of flags, Mr Biden was not able to give the acceptance speech his aides had hoped.
But he hit notes of unity, seemingly aimed at cooling the temperature of a heated, divided nation.
He said: “We have to remember the purpose of our politics isn’t total unrelenting, unending warfare.
“No, the purpose of our politics, the work of our nation, isn’t to fan the flames of conflict, but to solve problems, to guarantee justice, to give everybody a fair shot.”
Mr Trump’s campaign on Friday was mostly quiet, a dramatic difference from the day before, when officials held a morning call projecting confidence and then a flurry of press conferences announcing litigation in key states.
A handful of states remained in play on Friday evening: Georgia, North Carolina too early to call along with Pennsylvania and Nevada.
With his pathway to re-election appearing to greatly narrow, Mr Trump was testing how far he could go in using the trappings of presidential power to undermine confidence in the vote.
On Thursday, he advanced unsupported accusations of voter fraud to falsely argue that his rival was trying to seize power.
It was 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.
He pledged further legal action on Friday night, tweeting that “Joe Biden should not wrongfully claim the office of the President. I could make that claim also. Legal proceedings are just now beginning!”
Mr Trump did claim that he won late on Election Night.
He also tweeted that he had “such a big lead in all of these states late into election night, only to see the leads miraculously disappear as the days went by,” although it was well known that votes cast before Tuesday were still being legally counted.
