How can an amendment to the Constitution be proposed?

An amendment to the Constitution can be proposed through two primary methods as outlined in Article V of the Constitution: either by a two-thirds vote in both houses of Congress or by a national convention called for by two-thirds of the state legislatures. This method emphasizes the significant consensus required for constitutional change, reflecting the framers' intention to ensure that amendments have considerable support across both Congress and the states.

Proposing amendments via a simple majority in one house of Congress does not meet the high threshold established for such profound changes to the nation’s foundational legal framework. A national referendum, while a concept often discussed in the context of democracies, is not a recognized method under the U.S. Constitution for proposing amendments. Lastly, requiring a unanimous vote from state legislatures is excessive and impractical, as it would impose an impossible standard that could prevent any amendments from being proposed, thereby stifling the constitutional amendment process altogether.