Joe Biden’s probability of quitting the U.S. presidential race climbed about six percentage points on Thursday, hitting 65%, according to traders on crypto-based prediction market Polymarket.

The odds increased ahead of Biden’s first press conference in months this evening U.S. time. Concerns about his age and cognitive health have led to widespread calls among prominent Democrats and donors, including actor George Clooney, for the president to step aside, despite his insistence he is staying in.

Biden’s chances of becoming the Democratic nominee slid 16 points on Thursday to 38%, according to a separate Polymarket contract.

A third contract, on who will win the presidency, now gives Biden a 10% chance of victory, down four points on the day; Vice President Kamala Harris has 19% odds, while presumptive Republican candidate Donald Trump is at 61% on Polymarket.