28 U.S.C. § 2409

Any civil action by any tenant in common or joint tenant owning an undivided interest in lands, where the United States is one of such tenants in common or joint tenants, against the United States alone or against the United States and any other of such owners, shall proceed, and be determined, in the same manner as would a similar action between private persons. Whenever in such action the court orders a sale of the property or any part thereof the Attorney General may bid for the same in behalf of the United States. If the United States is the purchaser, the amount of the purchase money shall be paid from the Treasury upon a warrant drawn by the Secretary of the Treasury on the requisition of the Attorney General.