How many votes are needed to override a veto?

Two-thirds of those voting in each chamber, the House of Representatives and the Senate, are needed to override a presidential veto. This requirement is set by Article I, Section 7 of the Constitution. The two-thirds threshold applies to those present and voting, not to the entire chamber's full membership. If all 100 senators vote, the threshold is 67. If all 435 representatives vote, the threshold is 290. If fewer members are present, the threshold scales down accordingly.

The two-thirds rule applies independently in each chamber. The override vote occurs first in the chamber that originally passed the bill. If two-thirds of that chamber votes to override, the bill goes to the other chamber, which holds the same vote. Both chambers must reach the two-thirds threshold for the override to succeed. If either chamber falls short, the override fails and the bill remains vetoed.

The two-thirds threshold is high. Most legislation passes with simple majorities (a simple majority is more than 50 percent). Achieving two-thirds typically requires significant bipartisan support. In recent decades, neither party has held two-thirds majorities in either chamber, meaning override votes generally require members of the President's own party to defect. The high threshold is one reason most vetoes stand. Of more than 2,500 vetoes in American history, only about 110, or roughly 4 percent, have been overridden.

The framers chose the two-thirds threshold deliberately as part of the Constitution's checks and balances. They wanted Congress to be able to overcome a presidential veto when there was strong support for legislation, but they did not want overrides to be easy. The two-thirds requirement was meant to ensure that veto overrides reflected truly broad consensus, not just majority opinion.

The two-thirds threshold also appears elsewhere in the Constitution. Two-thirds of the Senate must vote to convict in an impeachment trial. Two-thirds of both chambers must vote to propose a constitutional amendment (which then requires ratification by three-fourths of the states). Two-thirds of the Senate must vote to ratify a treaty. Each of these supermajority requirements reflects the framers' concern that especially important decisions should require broader agreement than ordinary legislation.

Some have proposed lowering the override threshold to a simple majority or other levels, arguing that the two-thirds requirement gives the President too much power and contributes to legislative gridlock. Such changes would require a constitutional amendment.