A copy of each special message transmitted under section
683 or
684 of this title, shall be transmitted to the Comptroller General on the same day it is transmitted to the House of Representatives and the Senate. In order to assist the Congress in the exercise of its functions under section
683 or
684 of this title, the Comptroller General shall review each such message and inform the House of Representatives and the Senate as promptly as practicable with respect to—