Democratic candidate Joe Biden has pulled ahead of Donald Trump in Pennsylvania, a key state in the US presidential race, results data show.
Mr Biden is leading by nearly 10,000 votes, with 98% counted. If he takes the state, he will win the election.
Earlier, Mr Biden edged ahead of his Republican rival in Georgia, another key battleground state, where a recount will now be held.
Meanwhile, the Trump campaign said: “This election is not over.”
In a statement, Trump campaign lawyer Matt Morgan claimed without evidence that ballots in Georgia were “improperly harvested” and that in Pennsylvania election observers were not given “meaningful access” to counting, despite a judge’s order allowing them further access on Thursday.
What’s the current state of the race?
Mr Biden currently has 253 Electoral College votes, while Mr Trump has 214. To win the White House, a candidate needs 270.
Some news organisations have a higher tally for Mr Biden, having projected a win for the Democrat in Arizona. But the BBC considers the state too early to call.
Pennsylvania, where Mr Biden was born, has 20 Electoral College votes. If the Democrat wins it, he will secure the victory with 273 votes.
Pennsylvania has always been a major political battleground. The state voted Democrat in six consecutive races before it swung to Mr Trump in 2016.
In Georgia, Mr Biden is currently leading with more than 1,500 votes, with 99% of the ballots counted. Georgia’s secretary of state said there would be a recount because the margin was so small.
Georgia is a traditionally Republican state and has not been won by a Democrat in a presidential race since 1992.
Mr Trump’s team says legal challenges and recounts in some states will favour them.
Bob Bauer, a Biden campaign lawyer, says the lawsuits are legally “meritless” and designed “to message falsely about what’s taking place in the electoral process”.
The vote is also currently too close to call in Nevada and North Carolina.
A win in just Pennsylvania, or two of the other four remaining states would be enough to confirm Mr Biden as president-elect.
Mr Trump, meanwhile, would need to win Pennsylvania and three of the remaining four states.
Overnight, Joe Biden pulled ahead of Donald Trump in Georgia. And with the latest batch of vote totals released, Biden has taken the lead over Trump in Pennsylvania.
Georgia’s 16 electoral votes would be enough to guarantee at least a tie in the Electoral College, pending results from the other uncalled states. Pennsylvania would single-handedly deliver the White House to Biden.
The trendlines in both states are clear, as well. Biden has been netting more votes with each new tally, and he’s only going to extend his lead in both states. There are fewer ballots to count in Georgia, so the state is going to stay close – and the recount has already been announced.
By the time all is said and done, however, Biden should lead in Pennsylvania by more than Donald Trump won the state by in 2016.
The drama from these last few days is the result of the process by which these states have counted their votes – tallying mailed-in ballots that have tilted heavily toward Biden after in-person ones, which have been in Trump’s favour.
If the process had been reversed, the picture on election night would have been much clearer from the start.
After the dust settles, the results are what they are. And in Delaware, Biden is probably smiling.
What have the candidates said?
Mr Trump has made unsubstantiated claims of election fraud.
Speaking from the White House on Thursday, the president said: “If you count the legal votes, I easily win. If you count the illegal votes they can try to steal the election from us.”
The president added: “We were winning in all the key locations, by a lot actually, and then our numbers started getting miraculously whittled away in secret.”
“There’s been a lot of shenanigans and we can’t stand for that in our country,” he said.
Mr Trump actively discouraged his supporters from voting by mail, while Mr Biden urged his voters to do so, and it is these postal ballots that are now being tallied in the key states.
Election analysts also say the president’s claims of Democratic electoral corruption are undermined by the better-than-expected performance of his fellow Republicans in congressional races across the map.
Several US networks cut their feeds of Mr Trump’s speech, while numerous Republicans criticised the remarks.
In a brief televised address, Mr Biden appealed for calm across the country and again expressed confidence he would be declared the winner.
“Democracy is sometimes messy,” he said. “It sometimes requires a little patience as well.”