Donald Trump made a series of unsubstantiated allegations to claim he is being cheated out of re-election after his Democratic opponent, Joe Biden, appealed for calm and patience.
The Republican incumbent alleged he is the victim of interference from “phoney polls” as well as “big media, big money and big tech” after launching legal battles to stay in office.
In an extraordinary White House press conference, Mr Trump said: “If you count the legal votes, I easily won. If you count the illegal votes, they can try to steal the election from us.”
The president’s remarks, all of which came without any evidence, came in stark contrast to Mr Biden’s earlier on Thursday when he stressed “each ballot must be counted” and said he has “no doubt” he will eventually win.
The election is still too close to call after polls closed on Tuesday, but former vice-president Mr Biden remains the favourite after winning three key battleground states.
After securing victories in Wisconsin and Michigan, the Democrat had 264 electoral college votes and needed to secure one of Georgia, Nevada, North Carolina or his birth state Pennsylvania to reach the necessary 270 to win the White House race.
Mr Trump, however, must win all four states. He continued to question the legitimacy of the election and began legal action to either stop the counting of votes or insist his team be given greater access to scrutinise the process.
Addressing the White House press room, the president baselessly said media polling was “election interference in the truest sense of that word”.
He continued his criticism of postal votes and said the Republicans were “winning in all the key locations” but that their leads then “started miraculously getting whittled away in secret”.
“The pollsters got it knowingly wrong,” Mr Trump said. “There was no blue wave that they predicted, they thought there was going to be a big blue wave – that was false, it was done for suppression reasons.”
Major US TV networks ABC, CBS and NBC all pulled away from covering Mr Trump’s claims. MSNBC also interrupted the president, but the Fox News Channel and CNN aired the president’s address in full.
Network personalities had sharply criticised Mr Trump after his angry, middle-of-the-night speech following Election Day, but aired that talk in full.
Unlike in Mr Trump’s defiant press conference late on election night, vice president Mike Pence was this time not by his side, an absence immediately interpreted by some analysts as potentially reflecting a level of disagreement evident from several Republican party figures over the position Mr Trump has taken.
Mr Pence, however, later tweeted that he stood with the president in calling for every “legal” vote to be counted.
I Stand With President @realDonaldTrump. We must count every LEGAL vote.— Mike Pence (@Mike_Pence) November 6, 2020
As the presidency remained on a knife-edge, Mr Biden used a measured tone to say “democracy is sometimes messy, it sometimes requires a little patience”.
“Each ballot must be counted and that’s what we’re going to see going through now and that’s how it should be,” he said from a stage in his hometown of Wilmington, Delaware, next to his running mate Kamala Harris.
“We continue to feel very good about where things stand, we have no doubt that when the count is finished senator Harris and I will be declared the winners.
“So I ask everyone to stay calm, all the people to stay calm, the process is working, the count is being completed and we’ll know very soon.”
Elections are run by individual state, county and local governments and Mr Trump’s public comments have no impact on the tallying of votes across the country.
The Trump campaign requested a recount in Wisconsin and filed lawsuits in Pennsylvania, Michigan and Georgia.
But judges in Michigan and Georgia dismissed the actions launched by the Trump campaign.
Additional legal action was also expected in Nevada, the campaign indicated.
Mr Biden’s campaign manager, Jen O’Malley Dillon, said the president “knows he is losing” and had chosen to “push a flailing strategy, designed to prevent people’s votes from being counted”.
The bitterly fought election and the protracted results process have added to tensions on the streets in some American cities.
Police in Seattle and Portland arrested more than a dozen people as hundreds took to the streets to demand a full count of all presidential election votes and a halt to President Trump’s court challenges.
Pro-Trump supporters have also converged on vote-counting centres in cities such as Detroit and Phoenix.