The Congress, whenever two thirds of both Houses shall deem it necessary, shall propose Amendments to this Consti- tution, or, on the Application of the Legislatures of two thirds of the several States, shall call a Convention for pro- posing Amendments, which, in either case, shall be valid to all Intents and Purposes, as part of this Constitution, when ratified by the Legislatures of three fourths of the several States, or by Conventions in three fourths thereof, as the one or the other Mode of Ratification may be proposed by Con- gress.3