A new joint venture between three streaming leaders could create a monopoly problem in sports television, three lawmakers warn US regulators in a letter first reported by The Athletic.

Sens. Elizabeth Warren (D-MA) and Bernie Sanders (I-VT) and Rep. Joaquin Castro (D-TX) are asking law enforcers to investigate the joint venture between Disney, Fox, and Warner Bros. to create a new service, Venu Sports. The streaming service is expected to include sports networks from across the three companies’ portfolios, including ESPN, Fox, and TNT. Last week, the companies announced that Venu Sports will cost $42.99 per month.

In the letter to Justice Department antitrust chief Jonathan Kanter and Federal Communications Commission Chair Jessica Rosenworcel, the lawmakers said that Venu, “would be poised to control more than 80% of nationally broadcast sports and more than half of all national sports content, putting it in a position to exercise monopoly power over televised sports.” That, in turn, could empower the new venture “to discriminate against competitors and increase prices for consumers.”

They warn that the venture raises concerns under antitrust law and may be inconsistent with national ownership cap rules, barring a single company from owning stations reaching more than 39 percent of US households. In practice, they write, competitors to Venu Sports would need to negotiate with Disney, Fox, and Warner Bros. “for access to over half of the major sporting licensing rights while simultaneously competing against these companies to offer the best product to broadcast or stream these programs.”

Lawmakers have had an eye on the deal for a while now. Rep. Jerry Nadler (D-NY), the top Democrat on the House Judiciary Committee who has supported tech antitrust legislation, said in April that he and Castro were “seeking more information to make sure this consolidation does not result in higher prices and fewer choices for consumers.” Streaming competitors also raised alarms about the joint venture. In May, Fubo, DISH Network, DirecTV, and Newsmax were among the organizations that urged key congressional committees to investigate the deal. The companies warned that Venu Sports would have “the power and incentive to drive out its competitors.”

The joint venture is the “continuation” of a trend toward consolidation in television, according to the lawmakers, which has resulted from mergers and acquisitions in the sector. “The description of this deal as a ‘joint venture’ should not prevent antitrust and telecommunications regulators from giving it the scrutiny it deserves,” they wrote.

The FCC declined to comment on the letter and the DOJ did not immediately respond to a request for comment. In an email “on behalf of the three entities,” ESPN spokesperson Katina Arnold declined to comment.