MADISON, Wis. (AP) — Wisconsin’s Josh Kaul has joined a multistate coalition of attorneys general investigating Facebook over antitrust issues.

The bipartisan group includes attorneys general from more than 30 states as well as from the District of Columbia and Guam.

The probe was announced last month . Kaul said Tuesday that he was joining it.

Critics fear that Facebook can squash competitors either by buying them or mimicking their services, reducing options for consumers looking for comparable services that do less tracking for targeted advertising.

Kaul said in a statement that a lack of competition can stifle innovation and hurt consumers.