More than half of Democrats in a new poll Thursday say Joe Biden should end his reelection bid after his debate performance against Donald Trump, although they remain in a dead heat despite the president's poor showing.
Both candidates received 46 percent support among registered voters in the Washington Post-ABC News-Ipsos survey, almost identical to the results of an ABC News-Ipsos poll in April.
Some 56 percent of Democrats and two-thirds of Americans overall want Biden to quit the White House race. Half of all respondents said his Republican challenger should drop out.
Were Vice President Kamala Harris to replace her boss as the Democratic nominee she would fare better, according to the poll, scoring 49 percent against Trump's 47 percent.
Biden, 81, is facing a growing clamour among nervous Democrats to consider ending his campaign amid doubts over his mental fitness raised by his disastrous debate performance in Atlanta last month, when he struggled to finish sentences or communicate a coherent message.
Others, including influential former House speaker Nancy Pelosi, have stopped short of urging Biden to quit while stressing he needs to make a quick decision on his future -- even with Biden insisting he is ploughing on.
Hollywood actor and supporter George Clooney ratcheted up the pressure on Biden in a column calling on him to drop out, just weeks after holding a glitzy fundraiser for the president.
All eyes are on his first post-debate press conference later Thursday, at the NATO summit in Washington -- a potential inflection point that many Democrats feel could seal the fate of his reelection bid.
Biden has given fewer news conferences than his predecessors and interviews are rare, leading critics to accuse the White House of shielding from the public the effects of age on America's oldest president.
Some 85 percent of respondents in the new poll said Biden is too old for a second term -- up from 81 percent in April and 68 percent around a year ago -- while 60 percent say Trump is too old.
The Republican scored 55 percent in the April survey.