; (2) serve as independent trustee, preserve trust assets, and enforce the trust; or (3) file suit in the United States district court for the district in which the dealer resides to enjoin the dealer’s failure to perform the duties required by section 318, preserve trust assets, and to enforce the trust. Attorneys employed by the Secretary may, with the approval of the Attorney General, represent the Secretary in any such suit. Nothing herein shall preclude unpaid sellers from filing suit to preserve or enforce the trust. .