Mr Douglas, who has previously fundraised for the president, said he was disappointed at his "inability" to "challenge all the lies" of Donald Trump during the first debate.
His comments follow an op-ed written in the New York Times by George Clooney, who is a major fundraiser for the Democratic party, calling for President Biden to stand aside.
US President Joe Biden has admitted he "screwed up" in last week's debate against Donald Trump, but has vowed to fight on in the election race and moved to reassure key allies.
George Clooney’s opinion piece in the NYT here.
