If, on or about the time of submitting any such amendment, Congress, in the resolution submitting the same, or by statute, shall prescribe the manner in which the conventions shall be constituted, the preceding 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 the State who may by the resolution or statute be authorized or directed to take any action to constitute such a convention for this State are hereby authorized and directed to act thereunder and in conformity thereto, with the same force and effect as if acting under a statute of this State.