Two days after United States vice president Kamala Harris became the odds-on favorite to be the Democratic candidate for the nation's top office, the embattled incumbent president Joe Biden is again seen as most likely to top the ticket in November, according to the crypto betting site Polymarket.

Biden's chances of being the Democratic nominee rose to 42% on the site on Friday, as Harris' prospects fell to 36%. More than $88 million has been wagered so far on the question of who will be the Democratic nominee.

On the popular prediction market, Harris flipped Biden earlier this week in the tumultuous aftermath of the first presidential debate, where the president's faltering performance triggered concerns over his viability as a candidate and widespread speculation over a potential replacement.

With odds largely holding above 40% since Tuesday, Harris had held the top spot for nearly two days—although Biden's odds spiked after he told supporters later that day that “I’m in this race to the end and we’re going to win.”

Another strong statement from Biden appears to have played a factor in his resurgence, with Polymarket noting on Twitter (aka X) that the president gave a “fiery speech” in Wisconsin on Friday, again vowing to stay in the race. Biden's odds of dropping out—a separate Polymarket wager, carrying $11 million in bets—dipped to 59%, the site noted.

Those odds, which have rebounded somewhat to 61% at the time of writing, were as high as 82% on Tuesday.

In contrast to the prediction market volatility seen for Democratic party candidates—where Polymarket users give former first lady Michelle Obama a 7% chance of being the party's presidential candidate, despite her frequent and clear assertions that she will not run—things have held pretty steady for Biden's presumed challenger.

Former president Donald Trump has been favored overall to be the next U.S. president, according to Polymarket, holding a more than 60% chance of winning for more than two weeks. In that wager—with more than $220 million on the line—Harris still has the favor of Polymarket bettors over Biden, with 16% to 13% odds of winning, respectively.

Edited by Andrew Hayward