Four Connecticut lawmakers are demanding a federal probe of the U.S. Department of Interior’s (DOI) decision to sit on the request of tribal casino operators to expand their operations in the state.

Politico reported that U.S. Sens. Richard Blumenthal and Chris Murphy and U.S. Reps. John Larson and Joe Courtney prodded the federal Office of the Inspector General to investigate the DOI for what they described as “highly unusual decision to take no action” on the state’s request to amend two tribal gaming compacts.

Tribal operators Foxwoods Resort Casino and Mohegan Sun needed the DOI’s nod to be able to proceed with the construction of a casino off tribal land in East Windsor.

In a letter to the Inspector General, the four lawmakers accused the DOI of refusing to talk to the members of the Connecticut delegation, who were tasked with explaining the proposed changes in the tribe’s gaming compacts, which are opposed by commercial casino operator MGM Resorts International and its allies.