Pollster Nate Silver on Monday questioned whether President Joe Biden dropping out of the presidential race now could give Democrats the best chance of defeating former President Donald Trump.

Biden’s approval hit the lowest point of his presidency on Sunday at 37.4%, according to FiveThirtyEight.com. Silver in a post on X acknowledged Biden’s withdrawal from the race would be a substantial risk, but said it’s a possibility that staying in the running could be even more risky.

“Biden just hit a new all-time low in approval (37.4%) at 538 yesterday,” Silver posted. “Dropping out would be a big risk. But there’s some threshold below which continuing to run is a bigger risk. Are we there yet? I don’t know. But it’s more than fair to ask.”

“What’s clearer IMO [in my opinion] is that Democrats would have been better served if Biden had decided a year ago not to seek a second term, which would have allowed them to have some semblance of a primary process and give voters a say among the many popular Democrats across the country,” he added.

Silver in May urged Biden to contemplate dropping out if it appears in August that he may lose the election, which is when the Democratic National Convention is scheduled to take place in Chicago.

“If Biden is still struggling in August he needs to consider stepping aside,” Silver posted on X. “It’s not a great situation for Ds either way, but you have to do due diligence on the question. It’s an important election, obviously. It shouldn’t be taboo to talk about.”

Former President Barack Obama’s former senior adviser and chief strategist David Axelrod told comedian Bill Maher in May that it’s too late to replace Biden.

“Listen, that is a fantasy that I hear a lot,” Axelrod said. “Right now, he is the nominee of the Democratic Party.”

“This is not 1968 where the convention is gonna decide, we changed the rules, voters nominate a candidate, they’ve nominated Joe Biden and he’s not going anywhere,” he continued. “There’s no delegation of elders … who are going to go to the White House and tell him that he can’t run.”