Biden, the former vice president, was chipping away at the Republican incumbent’s leads in Pennsylvania and Georgia even as he maintained narrow advantages in Nevada and Arizona, moving closer to securing the 270 votes in the state-by-state Electoral College that determines the winner.

Biden would become the next president by winning Pennsylvania, or by winning two out of the trio of Georgia, Nevada and Arizona.

Trump’s likeliest path appeared narrower – he needed to hang onto Pennsylvania and Georgia while overtaking Biden in either Nevada or Arizona.

Final results in each state could take days.

Mr. Trump has sent a series of Twitter posts that made claims of fraud and calling for vote counting to cease.

His campaign, meanwhile, pursued a flurry of lawsuits in Georgia, Michigan, Nevada and Pennsylvania, though judges in Georgia and Michigan quickly rejected the challenges.

Legal experts said the cases had little chance of affecting the electoral outcome.