Sen. Richard Blumenthal contacted commissioners of six major U.S. sports leagues Thursday about gambling partnerships. The Democrat expressed concerns about "gambling's ugly takeover of sports," asking leagues to explain how they're protecting game integrity and preventing addiction. His letters to the NFL, NBA, NCAA, MLB, NHL and MLS request information by May 1 about arrangements with sportsbooks and prediction markets that have become increasingly prevalent across professional sports.

Blumenthal noted gambling has "permeated every aspect" since the federal ban was overturned eight years ago. He highlighted how prediction markets have "only made the problem worse," with fans rooting for payouts rather than their teams. While the NCAA has no sportsbook partnership, MLB, MLS and NHL recently signed deals with prediction markets, with the NFL and NCAA expressing safety concerns about these arrangements that monetize athletes' performances and even their health.

The senator waded into the legal debate surrounding prediction markets, asking leagues how they'll ensure partnerships comply with state laws. His inquiry comes as courts grapple with whether prediction markets fall under federal or state jurisdiction. Blumenthal recently introduced legislation banning insider trading on prediction markets and restricting users under 21, reflecting growing regulatory scrutiny of this rapidly expanding industry that has blurred traditional lines between sports and gambling.