The knife-edge US presidential race tilted toward Democrat Joe Biden early Thursday, with wins in Michigan and Wisconsin bringing him close to a majority, but President Donald Trump claimed he was being cheated and went to court to try and stop vote counting.
Tallying of votes continued through a second night in the remaining battleground states where huge turnout and a mountain of mail-in ballots sent by voters trying to avoid exposure to the coronavirus made the job all the harder.
Both candidates still had the possibility of reaching the crucial number of 270 electoral votes representing a majority of states, thereby winning the White House.
But momentum shifted to Biden, who made a televised speech from his hometown of Wilmington, Delaware, to say that "when the count is finished, we believe we will be the winners."
Wins in Michigan, Wisconsin and Arizona
By flipping the northern battlegrounds of Michigan and Wisconsin, and also winning formerly pro-Trump Arizona, Biden reached 264 electoral votes against 214 so far for Trump.
To reach 270 Biden will be hoping next to add the six electoral votes from Nevada, where he had a tiny lead, or, even better, the larger prizes of hard-fought Georgia or Pennsylvania.
In stark contrast to Trump's unprecedented rhetoric about being cheated, Biden sought to project calm, reaching out to a nation torn by four years of polarising leadership and traumatised by the Covid-19 pandemic, with new daily infections Wednesday close to hitting 100,000 for the first time.
"We have to stop treating our opponents as enemies," Biden said. "What brings us together as Americans is so much stronger than anything that can tear us apart."
Legal dispute launched
However, Trump claimed victory unilaterally and made clear he would not accept the reported results, issuing unprecedented complaints -- unsupported by any evidence -- of fraud.
"The damage has already been done to the integrity of our system, and to the Presidential Election itself," he tweeted, alleging without proof or explanation that "secretly dumped ballots" had been added in Michigan.
Trump's campaign announced lawsuits in Michigan, Pennsylvania and Georgia and demanded a recount in Wisconsin.
In Michigan, the campaign filed a suit to halt vote tabulation, saying its "observers" were not allowed to watch at close distances.
Troubles on the street in several cities
Tension also shifted to the streets.
In Detroit, a Democratic stronghold that is majority Black, a crowd of mostly-white Trump supporters chanted "Stop the count!" and tried to barge into an election office before being blocked by security.
US news networks showed an aggressive pro-Trump crowd also gathering outside a vote counting office in the important Arizona county of Maricopa, which includes the city of Phoenix.
Police and National Guard troops in camouflage trucks pursued far-left protesters around the US city of Portland as a riot was declared there late Wednesday.