What is the required congressional support to ratify a constitutional amendment?

Ratifying a constitutional amendment requires a two-thirds majority in both houses of Congress. This high threshold reflects the framers' intention to ensure that amendments reflect a broad consensus across the political spectrum before they can alter the nation's foundational document.

In Congress, achieving a two-thirds majority means that at least 67 of the 100 Senators must agree, and similarly, at least 290 of the 435 members of the House of Representatives must support the amendment. This process helps to prevent hasty changes to the Constitution and requires substantial bipartisan support, thus promoting stability and continuity in the governing framework of the United States.

The other options describe lower thresholds or processes that do not accurately represent the rigorous procedure established for constitutional amendments. A simple majority refers to a majority of those present and voting in a single house, which is not sufficient for an amendment. Unanimous consent suggests that every member must agree, which is impractical and not required for amendments. Lastly, a 3/4 majority pertains to the state legislatures' role in the ratification process, rather than the initial congressional approval, making it an incorrect choice in this specific context.