If at or about the time of submitting any such amendment, Congress shall, either in the resolution submitting the same or by a statute, prescribe the manner in which the conventions shall be constituted, and shall not except from the provisions of such statute or resolution such states as may theretofore have provided for constituting such conventions, the provisions of this chapter shall be inoperative, the convention shall be constituted and shall operate as the resolution or act of Congress shall direct, and all officers of this State who may by the resolution or statute be authorized or directed to take any action to constitute such a convention for this State shall act thereunder and in obedience thereto with the same force and effect as if acting under a statute of this State.