The Trump administration’s warehouse buying spree is drawing interest from one of the largest private prison contractors, although a top executive acknowledged Thursday that retrofitting the facilities to detain immigrants will be a challenge.

Geo Group is “cautiously participating” in the procurement process for running the warehouses and evaluating select sites, the company’s executive chair, George Zoley, told investors during an earnings call. The Department of Homeland Security wants to hold as many as 8,500 people in some of the several warehouses it has purchased in Arizona, Pennsylvania, Georgia and Texas.