President Donald Trump is not conceding to President-elect Joe Biden, promising unspecified legal challenges seeking to overturn the outcome of the race for the White House.

Trump said in a statement that "our campaign will start prosecuting our case in court to ensure election laws are fully upheld and the rightful winner is seated."

Trump was at his Virginia golf course when the presidential race was called for Biden on Saturday. Biden clinched his victory with a win in Pennsylvania, the state where he was born.

In recent weeks, Trump has alleged - without evidence - widespread fraud and misconduct in the election.

His comments have drawn bipartisan rebuke from election officials and lawmakers as dangerous attempts to undermine public confidence in the vote.