BBC.COM-media captionJoe Biden: I’m not here to declare we won
Donald Trump and Joe Biden each claim to be ahead in the US presidential election, even as the final outcome hangs on a razor’s edge and both sides ramp up for legal action.
The Trump campaign is challenging vote counts in the key states of Wisconsin, Georgia, Pennsylvania and Michigan.
The BBC projects Mr Biden won Michigan. US media forecast he took Wisconsin. No result has emerged in Pennsylvania.
Winning all three of these Rust Belt states would hand Mr Biden victory.
Democratic candidate Mr Biden stopped short of declaring he had won, but said he was confident he was on course to defeat Republican Mr Trump.
Overall turnout in Tuesday’s election was projected to be the highest in 120 years at 66.9%, found the US Election Project.
Mr Biden had the support of 70.5 million voters, the most won by any presidential candidate ever. Mr Trump has pulled in 67.2 million votes, four million more than he gained in 2016.
The bitter election race was dominated by the coronavirus pandemic, which hit a new record high of 103,000 daily cases in the US on Wednesday, according to the Covid Tracking Project.
What are the campaigns saying?
On Wednesday afternoon, Mr Biden told reporters in Wilmington, Delaware: “When the count is finished we believe we will be the winners.”
He added: “I will govern as an American president. The presidency itself is not a partisan institution.”
He said he was feeling “very good” about Pennsylvania, although the campaign of President Trump said it was “declaring victory” in the state on the count of “all legal ballots”.
Senior Trump campaign aide Jason Miller said: “By the end of this week it will be clear to the entire nation that President Trump and Vice-President Pence will be elected for another four years.”
Can Trump still win?
Mr Biden has the edge in the race to accumulate the 270 Electoral College votes needed to win the White House. The Democrat has 243 votes, while the Republican has 214.
In the US election, voters decide state-level contests rather than a single, national one. Each US state gets a certain number of electoral college votes partly based on its population and there are a total of 538 up for grabs.
If Mr Trump does lose Wisconsin (10 Electoral College votes), he must win Georgia (16 votes), North Carolina (15), Pennsylvania (20) and either Arizona (11) or Nevada (6) to prevail.
The president has a one-point lead in both North Carolina and Georgia and the two candidates were neck-and-neck in Nevada with most votes counted. The Trump campaign is hopeful it can still take Arizona.
Mr Biden has a nearly three-point advantage in the once reliably conservative sunbelt state with 85% of votes counted. CBS has categorised it as a “likely” win for the Democrat.
But the state’s Republican Governor Doug Ducey said in a statement on Wednesday that “the results have shifted greatly hour by hour” with hundreds of thousands of votes outstanding.
What legal challenges are afoot?
The Trump campaign said the president would formally request a Wisconsin recount, citing “irregularities in several Wisconsin counties”.
Incomplete results indicate the margin between Mr Trump and Mr Biden in Wisconsin is less than one percentage point, which allows a candidate to seek a recount.
The campaign also filed a lawsuit in Michigan to stop counting there because it contended it had been denied “meaningful access” to observe the opening of ballots and the tally.
In Detroit, Michigan, police were called on Wednesday afternoon to guard the doors to a vote-counting facility as some protesters outside demanded access to monitor the process. According to the Detroit Free Press, there were already some 200 people observing the vote inside the building.
Officials were seen covering up the windows to the TCF Center, where postal ballots were being tabulated.
The Trump campaign also filed two lawsuits in Pennsylvania to halt all vote counting “until there is meaningful transparency”.
The president has a three-point lead in the Keystone state, but many thousands of votes remain to be counted.
Mr Trump is also suing Georgia to halt the vote count there. His campaign said a Republican poll observer in the southern state had witnessed 53 late absentee ballots being illegally added to a pile of votes in Chatham County.
Mr Trump won Wisconsin, Michigan and Pennsylvania in his against-all-odds 2016 victory.
In the early hours of Wednesday, he announced from the White House that he had won his re-election bid and was prepared to take the matter to the Supreme Court.
The Trump campaign is asking Republican donors to help fund legal challenges.
Republican National Committee Chairwoman Ronna McDaniel said: “The fight’s not over. We’re in it.”
Mr Biden’s running mate, Kamala Harris, tweeted asking supporters to contribute $5 to help pay for litigation that could “stretch on for weeks”.
Biden campaign senior legal adviser Bob Bauer said there were no grounds for Mr Trump to invalidate lawful ballots.
What were the other key results?
Mr Biden’s hopes of a decisive early victory on election night were thwarted as Mr Trump defied pollsters’ predictions by over-performing in key battlegrounds.
The president held several important states, including Texas, Ohio and Iowa.
media captionUS election: Global media see US ‘held prisoner’ by election anxiety
He also comfortably won his adopted home state of Florida, the most hotly fought battleground of the night, despite two visits there by Mr Biden’s ally and former boss, ex-President Barack Obama.
But Mr Biden fended off his rival’s attempts to pick up New Hampshire and Minnesota.
What did the exit polls reveal?
Some political analysts were surprised by data that showed Mr Trump doubled his support among black voters to 12%, compared with four years ago.
He also boosted his vote share among Hispanic men to 36%, according to the exit polls, compared with 28% in 2016.
African Americans and Latinos are two vital electoral blocs for Democrats.
The president shed votes, though, among white men, the demographic that propelled him to the White House four years ago.
However, Mr Trump also increased his support significantly among white women (55% on Tuesday versus 47% in 2016).
What about the congressional races?
Democrats dreamed of an electoral blue wave sweeping away a Republican party that has been recast in Mr Trump’s image. But those hopes were dashed.
Their chances of winning Senate control appeared to be dwindling as the dust settled from election day. Democrats won two seats in Colorado and Arizona, but lost another in Alabama.
A Senate race in North Carolina remained undecided, and another in Georgia was heading for a run-off vote in January.
Senate Majority Leader Mitch McConnell said he felt “pretty good” about the remaining contests. Republicans currently control the chamber by 53-47.
Mr McConnell and Trump ally Lindsey Graham were both re-elected in their seats of Kentucky and South Carolina respectively.
Republicans also held on to other Senate seats in Maine, Montana, Texas and Iowa.
There was another unexpected setback for Democrats in House of Representatives races. The party had hoped to gain 15 seats in the lower chamber of Congress, which they currently control.
Instead they face a reduced majority after seven of their incumbents lost and the party failed to beat a single Republican.
One of the incoming Republican lawmakers, in Georgia, has been described as a supporter of the fringe, pro-Trump QAnon conspiracy theory.