Tribal governments are mounting a last-minute lobbying blitz to secure language in landmark cryptocurrency legislation to address prediction markets, which tribal leaders say is an “existential” threat to their economies.

A coalition of more than 100 tribal leaders from across the country will fan out on Capitol Hill starting Tuesday — when the Senate is scheduled to take a key procedural vote on the Clarity Act (H.R. 3633; BGOV Bill Analysis), which would stand up a federal regulatory framework for the crypto industry under a newly empowered Commodity Futures Trading Commission.

The Clarity Act doesn’t explicitly address …