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 more than 13,000 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.”
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.
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In a statement later, Mr Trump said: “From the beginning we have said that all legal ballots must be counted and all illegal ballots should not be counted, yet we have met resistance to this basic principle by Democrats at every turn.
“We will pursue this process through every aspect of the law to guarantee that the American people have confidence in our government. I will never give up fighting for you and our nation.”
A senior Trump administration official has told CBS News Mr Trump does not plan to concede in the event of a victory declaration by Mr Biden.
There are reports from the Biden campaign in Delaware that he will make a primetime address to the nation on Friday evening local time. This is believed to be dependent on the race being called by then.
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.
Election officials there said the count could take several days.
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.
Here’s the latest from the three other states that are still up for grabs:
- Mr Trump has cut the Democratic candidate’s lead in Arizona (11 electoral votes) to less than 44,000 votes, with 93% counted. The BBC’s partner CBS News has categorised the state, which carries 11 electoral college votes, as a “likely” win for Mr Biden
- Mr Trump had a lead of more than 76,000 in North Carolina (15 electoral votes), with 96% of votes tallied
- In Nevada, Mr Biden has an edge of more than 20,000 over Mr Trump. The state has six votes under the electoral college system. An election official there said the results from more than 51,000 postal ballots would be updated on Friday
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.”
Beyond allegations of irregularities, the Trump campaign has not presented any evidence.
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.
Utah Senator Mitt Romney on Friday joined a number of Republicans criticising Mr Trump’s comments. “He is wrong to say that the election was rigged,” Mr Romney tweeted.
Meanwhile, Mr Biden appealed for calm across the country and again expressed confidence he would be declared the winner.
“Democracy is sometimes messy,” he said in a brief televised address. “It sometimes requires a little patience as well.”
“The process is working. The count is being completed. And we’ll know very soon.”
As results trickle in, protests involving both sides have been held in major cities over the vote counting.
What legal action has the president taken?
Mr Trump has filed a barrage of lawsuits alleging irregularities and lack of transparency.
The president demanded a recount in Wisconsin, as is the right of any candidate who comes within 1% of his rival in total vote there.
But Mr Biden was leading by 20,000 votes in Wisconsin, and election analysts say previous recounts in the state have usually only altered the final tally by a few hundred votes.
Trump campaign lawsuits filed in Michigan and Georgia were tossed out by state courts on Thursday.
But in Pennsylvania, the Trump campaign won a legal victory when a state appeals court judge said Republican poll-watchers should be permitted a closer look at ballot processing.
The Republican party in Nevada said it had sent a report to the US Department of Justice on what it alleged were “at least 3,062 instances of voter fraud”. The party tweeted that thousands of individuals had been identified violating the law by casting ballots after moving out of the state.
Nevada’s Attorney General Aaron Ford told the BBC this week that all the evidence showed that the state had conducted a “free, safe and secure election”.
“We have safeguards in place to prevent fraud, such as signature verification, unique barcodes and other tools,” he said.