Democrat Joe Biden is now leading President Donald Trump in the battleground state of Georgia, putting the White House within his reach.
Victory in the state would take him over the 270 threshold of electoral college votes needed to win the presidency.
By Friday morning, Mr Biden overtook Mr Trump in the number of ballots counted in the battleground, a must-win state for Mr Trump that has long been a Republican stronghold.
Mr Biden now has a 917-vote advantage, as Georgia offers him a further 16 electoral votes that would add to his 253 to 214 lead in the race to 270 electoral college votes that determines the winner.
The contest is still too early for The Associated Press to call.
Mr Biden would become the next president by winning Pennsylvania, or by winning two out of the trio of Georgia, Nevada and Arizona.
Mr Trump's likeliest path appears narrower as he needs to hang onto both Pennsylvania and Georgia and also to overtake Mr Biden in either Nevada or Arizona.
Thousands of ballots are still left to be counted, many in counties where the former vice president was in the lead.
An analysis showed that Mr Biden’s vote margins grew as counties processed mail ballots cast in his favour.
There is a potential that the race could go to a recount. Under Georgia law, if the margin between Mr Biden and Mr Trump is under half a percentage point of difference, a recount can be requested.
The shift in Georgia came hours after Trump appeared at the White House to falsely claim the election was being "stolen" from him.
Mr Biden has been steadily chipping away at the Republican incumbent's lead in Pennsylvania as well. His deficit had shrunk to just more than 18,000 there by early on Friday, and was expected to continue falling with many of the ballots still to be counted being cast in Democratic areas.
Biden also maintained slim advantages in Arizona and Nevada. In Arizona, his lead narrowed to about 47,000 early on Friday and in Nevada he was ahead by about 11,500 votes.
As the country held its breath for a result in the White House race, Georgia and Pennsylvania officials expressed optimism they would finish counting on Friday.
Arizona and Nevada were still expected to take days to complete their vote totals.
