How are amendments to the United States Constitution primarily proposed?

Amendments to the United States Constitution are primarily proposed by a two-thirds vote in both houses of Congress, which consists of the House of Representatives and the Senate. This requirement is established in Article V of the Constitution, which outlines the formal process for proposing amendments. The rationale behind needing a supermajority reflects the framers' intent to ensure that any changes to the Constitution hold substantial support across a wide spectrum of elected representatives, thereby maintaining stability and continuity in the foundational legal framework of the nation.

The choices involving Presidential Executive Orders, public referendums, or state legislatures alone do not align with this constitutional requirement. Presidential executive orders are directives issued by the President to manage the operations of the federal government but do not pertain to constitutional amendments. Although public referendums can be a mechanism for states to decide on constitutional issues at a local level, they are not a method for proposing national amendments. State legislatures can play a role in the amendment process, primarily in ratifying proposed amendments, but they do not have the authority to propose amendments on their own. Thus, the correct method for proposing amendments is through a two-thirds vote in both houses of Congress.