1. Congress: The United States Congress, consisting of the Senate and the House of Representatives, has the authority to propose an amendment. A proposal can originate in either the Senate or the House, where the amendment resolution must pass by a two-thirds vote of both chambers.
2. Constitutional Convention: A constitutional convention can also propose amendments. Such a convention may be called upon the application of two-thirds of the state legislatures. Amendments proposed by a constitutional convention require ratification by three-fourths of the state legislatures or three-fourths of conventions held in each state.