The U.S. Justice Department on Friday called on a regulator to reject a voting trust Canadian Pacific has proposed as part of its takeover bid for Norfolk Southern, saying it risked harming competition in the rail industry.

The Justice Department said in a statement that it had told the Surface Transportation Board, which is reviewing the proposed merger, that the voting trust would “fail to preserve the independence of the merging railroads during the pendency of the transaction’s regulatory review and would risk harm to current and future competition.”