Article V of the Constitution requires a two-thirds vote in both the House and Senate to propose a constitutional amendment. Since 1789, Congress has proposed 33 amendments this way, and the states have ratified 27 of them. The president plays no role in the process—once Congress approves a proposed amendment by two-thirds majorities, it goes directly to the states for ratification without presidential signature.
This congressional proposal method is one of two ways to amend the Constitution, though it is the only method ever successfully used. The alternative allows two-thirds of state legislatures to call a constitutional convention, but this has never happened. The two-thirds threshold in Congress forces broad consensus across party lines, ensuring amendments reflect widely shared values rather than temporary political majorities. After Congress proposes an amendment, three-fourths of state legislatures or state conventions must ratify it before it becomes part of the Constitution. This dual supermajority requirement makes the Constitution extremely difficult to change, preserving stability while allowing adaptation when national consensus emerges.