What process requires a two-thirds vote in Congress?

Proposing an amendment to the U.S. Constitution indeed requires a two-thirds vote in Congress, specifically in both the House of Representatives and the Senate. This requirement reflects the framers' intent to ensure that any changes to the Constitution have broad support, recognizing the document's foundational importance to the nation’s governance.

The process for proposing an amendment can be initiated by either two-thirds of both chambers of Congress or by a constitutional convention called for by two-thirds of the state legislatures, although the latter method has never been used. This high threshold serves to safeguard constitutional integrity, making it challenging to modify the Constitution lightly or without substantial consensus.

In contrast, other processes such as passing a law or electing a Speaker of the House require a simple majority, reflecting the day-to-day operations of government where more frequent changes and decisions are necessary. Ratifying a treaty, while also requiring a two-thirds majority, is distinctly different from proposing an amendment as it pertains to international agreements rather than constitutional changes.