Democrat Joe Biden was pushing closer to the 270 electoral college votes needed to carry the White House, securing victories in the “blue wall” battlegrounds of Wisconsin and Michigan and narrowing President Donald Trump’s path to victory.
With a handful of states still contested, Mr Trump has tried to press his case in court in some key swing states.
It was unclear if any of his campaign’s legal manoeuvring over ballots would succeed in shifting the outcome in his favour.
Two days after the election, neither candidate had amassed the votes needed to win the White House.
But Mr Biden’s victories in the Great Lakes states left him at 264, meaning he was one battleground state away from becoming president-elect.
Mr Trump, with 214 electoral votes, faced a much taller hurdle.
To reach 270, he needed to claim all four remaining battlegrounds in Pennsylvania, North Carolina, Georgia and Nevada.
With millions of votes yet to be tabulated, Mr Biden had already received more than 71 million votes, the most in history.
On Wednesday, the former vice president said he expected to win the presidency but stopped short of declaring victory.
“I will govern as an American president,” Mr Biden said. ”There will be no red states and blue states when we win. Just the United States of America.”
It was a stark contrast to the approach of Mr Trump, who early on Wednesday morning falsely claimed that he had won the election.
His campaign engaged in legal action to try to improve the Republican president’s chances and cast doubt on the election results, requesting a recount in Wisconsin and filing suits in Pennsylvania, Michigan and Georgia.
Statewide recounts in Wisconsin have historically changed the vote tally by only a few hundred votes. Mr Biden led by more than 20,000 ballots out of nearly 3.3 million counted.
For four years, Democrats have been haunted by the crumbling of the blue wall, the trio of Great Lakes states Michigan, Wisconsin and Pennsylvania, on which their candidates had been able to count every four years.
But Mr Trump’s populist appeal struck a chord with white working-class voters and he captured all three in 2016 with a combined total of 77,000 votes.
The candidates waged a fierce fight for the states this year, with Mr Biden’s everyman political persona resonating in blue-collar towns, while his campaign also pushed to increase turnout among black voters in cities such as Detroit and Milwaukee.
It was unclear when a national winner would be determined after a long, bitter campaign dominated by the coronavirus and its effects on Americans and the national economy.
But as Mr Biden’s prospects improved, the US on Wednesday set another record for daily confirmed coronavirus cases, as several states posted all-time highs.
The pandemic has killed more than 233,000 people in the US.
Mr Trump spent much of Wednesday in the White House residence, huddling with advisers and railing against media coverage showing his Democratic rival picking up battlegrounds.
He used his Twitter feed to falsely claim victory in several key states and amplify unsubstantiated conspiracy theories about Democratic gains as absentee and early votes were tabulated.
Mr Trump's campaign manager Bill Stepien said the president would formally request a Wisconsin recount, saying there were irregularities in several counties.
And the campaign said it was filing suits in Michigan and Pennsylvania to halt ballot counting on the grounds that it was not given proper access to observe. Still more legal action was launched in Georgia.
At the same time, hundreds of thousands of votes were still to be counted in Pennsylvania.
Mr Trump’s campaign said it was moving to intervene in existing Supreme Court litigation over counting mail-in ballots there.
The campaign also argued that outstanding votes could still flip the outcome in Arizona, which went for Mr Biden, showing an inconsistency in its arguments over prolonged tabulation.
In other closely watched races, Mr Trump picked up Florida, the largest of the swing states, and held on to Texas and Ohio while Mr Biden kept New Hampshire and Minnesota.
Beyond the presidency, the Democrats had hoped the election would allow the party to reclaim the Senate and increase its majority in the House.
But while the voting scrambled seats in the House and Senate, it ultimately left Congress much like it began – deeply divided.
The candidates spent months pressing dramatically different visions for the nation’s future, including on racial justice, and voters responded in huge numbers, with more than 100 million people casting votes ahead of election day.
Mr Trump, in an extraordinary move from the White House, issued premature claims of victory and said he would take the election to the Supreme Court to stop the counting.
Senate majority leader Mitch McConnell discounted the president’s quick claim of victory, saying it would take a while for states to conduct their vote counts.
The Kentucky Republican said that “claiming you’ve won the election is different from finishing the counting”.
Vote tabulations routinely continue beyond election day, and states largely set the rules for when the count has to end.
In presidential elections, a key point is the date in December when presidential electors meet. That is set by federal law.
Dozens of Mr Trump's supporters chanting “Stop the count” descended on a ballot-tallying centre in Detroit, while thousands of anti-Trump protesters demanding a complete vote count took to the streets in cities across the US.
Protests, some focusing on the election, some about racial inequality, took place Wednesday in at least half a dozen cities, including Los Angeles, Seattle, Houston, Pittsburgh, Minneapolis and San Diego.
Several states allow mailed-in votes to be accepted after election day as long as they were postmarked by November 3.
That includes Pennsylvania, where such ballots can be accepted if they arrive up to three days later.
Mr Trump appeared to suggest that those ballots should not be counted and that he would fight for that outcome at the high court.
But legal experts were dubious about his declaration.
Mr Trump has appointed three of the high court’s nine justices including, most recently Amy Coney Barrett.
The Trump campaign on Wednesday pushed Republican donors to dig deeper into their pockets to help finance legal challenges.
Republican National Committee chairwoman Ronna McDaniel, during a donor call, spoke plainly: “The fight’s not over. We’re in it.”
