Prediction market traders now put the chances of the Clarity Act becoming law this year at just 39%, down sharply from a peak above 80% in February.

The odds on Polymarket, a betting platform where users wager real money on future events, have slid as a once-smooth path through Congress has jammed.

The Clarity Act, formally the Digital Asset Market Clarity Act, is the most ambitious attempt yet to write rules for the American cryptocurrency industry.

It would settle a decade-old turf war between two regulators, handing the Commodity Futures Trading Commission authority over most crypto trading while leaving the securities watchdog a narrower role.

Supporters say it would replace years of regulation-by-enforcement with clear…