President Joe Biden's train-wreck debate with Republican opponent Donald Trump followed a series of decisions by his most senior advisers that critics now point to as wrong-headed, interviews with Democratic allies, donors and former and current aides show.

Trump, 78, repeated a series of well-worn, glaring falsehoods during the 90-minute debate on Thursday, including claims that he actually won the 2020 election.

Biden, 81, failed to refute them and his fumbling, halting performance has sparked calls from Democrats for him to end his quest for a second term and for "soul-searching" or resignations among top aides.