Nearly two-thirds of Democrats say President Joe Biden should withdraw from the presidential race and let his party nominate a different candidate, according to a new poll, sharply undercutting his post-debate claim that “average Democrats” are still with him even if some “big names” are turning on him.

The new survey by the AP-NORC Center for Public Affairs Research, conducted as Biden works to salvage his candidacy two weeks after his debate flop, also found that only about 3 in 10 Democrats are extremely or very confident that he has the mental capability to serve effectively as president, down slightly from 40% in an AP-NORC poll in February.

The findings underscore the challenges the 81-year-old president faces as he tries to silence calls from within his own party to leave the race and tries to convince Democrats that he’s the best candidate to defeat Donald Trump. The poll was conducted mostly before Saturday’s assassination attempt on Trump at a campaign rally in Pennsylvania. It’s unclear whether the shooting influenced people’s views of Biden, but the small number of poll interviews completed after the shooting provided no early indication that his prospects improved.