The President by and with the consent of the Senate shall designate from time to time to attend a specified session or specified sessions of the General Conference of the Organization not to exceed five representatives of the United States and such number of alternates not to exceed five as he may determine consistent with the rules of procedure of the General Conference: Provided, however, That each such representative and each such alternate must be an American citizen. One of the representatives shall be designated as the senior representative. Such representatives and alternates shall each be entitled to receive compensation at such rates provided for members of the Senior Foreign Service under section 3962 of this title, or provided for Foreign Service officers under section 3963 of this title, as the President may determine, for such periods as the President may specify, except that no Member of the Senate or House of Representatives or officer of the United States who is designated under this section as a representative of the United States or as an alternate to attend any specified session or specified sessions of the General Conference shall be entitled to receive such compensation. Whenever a representative