Vice President Kamala Harris’ likelihood of securing the Democratic nomination for president has witnessed a dramatic surge on PolyMarket, the burgeoning crypto-based prediction market. On Tuesday, traders propelled her odds to over four times their previous value, reflecting a sharp increase in confidence.

By the afternoon in New York, “Yes” shares in a contract speculating on Harris becoming the nominee soared to 31 cents, signifying a 31% probability, a significant jump from the 7% earlier that day. Although the shares later adjusted to 23 cents, the rise underscored a growing sentiment among traders.

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Each share in these contracts pays out $1 (in USDC, a stablecoin tethered to the U.S. dollar) if the prediction materializes, otherwise, it returns zero. Officially, President Joe Biden remains the presumptive nominee for the Democratic Party. Nonetheless, a faction of his supporters is urging him to step aside, with some advocating for Harris to ascend, especially after Biden’s underwhelming performance in the recent debate against former President Donald J. Trump.

Rep. James Clyburn, D-S.C., expressed on television, “We should do everything we can to bolster her, whether it’s in second place or the top of the ticket.” Meanwhile, an op-ed in Newsweek by Tim Ryan, the first presidential candidate to endorse Biden in 2020, was more forthright: “Kamala Harris Should Be the Democratic Nominee for President in 2024.” Similarly, The Wall Street Journal analysis dubbed Harris “Biden’s Likeliest Replacement.”

The trend mirrored on PredictIt, a traditional prediction market where stakes are settled in dollars rather than crypto. Harris’ “Yes” shares more than doubled to 35 cents there. PredictIt’s volume for the Democratic nomination question totals $31 million, compared to PolyMarket‘s substantial $75 million.

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Under a settlement with the Commodity Futures Trading Commission, PolyMarket cannot operate within the U.S., unlike PredictIt, which operates under a regulatory exemption.

Tuesday marked PolyMarket’s fifth-largest trading volume day in its four-year history, with $5.7 million in activity, according to Dune Analytics data. June was a landmark month for PolyMarket, surpassing $100 million in volume for the first time.

PolyMarket’s largest contract, with $211 million in bets, speculates on the winner of the upcoming U.S. presidency, with Trump currently favored at a 66% chance of victory.