A two-thirds vote in Congress is required for a short list of specific actions spelled out in the Constitution and in each chamber’s own rules: overriding a presidential veto, proposing a constitutional amendment, ratifying a treaty, convicting an impeached official, expelling a sitting member, resolving a presidential disability dispute, lifting the 14th Amendment’s ban on office-holding, ending debate on a change to Senate rules, and suspending the House’s regular rules to pass a bill quickly. Most of these thresholds run against the members present and voting, assuming a quorum is in the chamber, so the raw number of votes needed can shift with attendance.
Overriding a Presidential Veto
When the President rejects a bill, it goes back to the chamber that introduced it, along with written objections. That chamber votes again, and if two-thirds of the members present approve, the bill goes to the other chamber for the same vote. Clear both, and the bill becomes law without the President’s signature. The Constitution also requires each override vote to be recorded by name, so every “yea” and “nay” lands in the official journal.
A few timing rules shape when an override is even possible. The White House has ten days (excluding Sundays) to act on a bill. If the President ignores it while Congress is still in session, it becomes law on its own. If Congress adjourns first, the bill dies by pocket veto and cannot be overridden. Congress’s only option then is to start over.
Proposing a Constitutional Amendment
Article V offers two routes, and both use a two-thirds threshold. The common route is a joint resolution passing the House and the Senate by two-thirds of the members present, with a quorum. The Supreme Court confirmed in the National Prohibition Cases that this counts members present, not the full membership.
The second route has never been used: if two-thirds of state legislatures apply, Congress must call a convention to propose amendments. Under either route, the President has no role. A proposed amendment goes straight to the states, where three-fourths must ratify.
Ratifying a Treaty
Treaty ratification is a Senate-only power. Article II, Section 2 requires at least two-thirds of the senators present to approve a treaty the President has negotiated. That gives a determined minority real blocking power over international agreements. Presidents often work around the requirement by using executive agreements, which rest on statutory authority or inherent executive power and do not need Senate approval. Executive agreements carry legal force, but they are not treaties in the constitutional sense.
Convicting an Impeached Official
Impeachment splits between the chambers. The House impeaches by simple majority, which functions like an indictment. The Senate then holds the trial, and conviction requires two-thirds of the senators present. A conviction removes the official from office automatically. The Senate can also hold a separate vote to disqualify the person from holding future federal office; that vote is distinct from the conviction itself.
Expelling a Member of Congress
Article I, Section 5 lets each chamber expel one of its own members for “disorderly Behaviour” by a two-thirds vote. Each chamber decides for itself what qualifies. Expulsion has been used only a handful of times, most notably during the Civil War. Lesser discipline, such as censure or reprimand, needs only a simple majority, so removing an elected member takes substantially broader agreement than publicly condemning one.
Resolving a Presidential Disability Dispute
Section 4 of the 25th Amendment covers the situation where the Vice President and a majority of the Cabinet declare the President unable to serve and the President disagrees. If that dispute reaches Congress, both chambers must vote by two-thirds that the President is unable to continue. Otherwise the President resumes full authority. Congress has twenty-one days from receiving the written challenge to decide, and if it is not already in session, it must assemble within forty-eight hours. The provision has never been invoked.
Lifting the 14th Amendment’s Office-Holding Ban
Section 3 of the 14th Amendment bars anyone who took an oath to support the Constitution and then engaged in insurrection from holding federal or state office. The same section lets Congress remove that disability by a two-thirds vote of each chamber. Congress used this authority in the Amnesty Act of 1872, which lifted the ban for most former Confederate officials, and again in 1898 to remove the remaining restrictions.
Ending Debate on a Senate Rules Change
Senate Rule XXII, the cloture rule, sets how debate ends. For most legislation and nominations, cutting off a filibuster takes 60 votes. But when the Senate moves to change its own standing rules, the cloture threshold rises to two-thirds of the senators present and voting: 67 votes if every senator participates. That elevated bar is a large part of why formal amendments to Senate rules are rare, and why the “nuclear option,” which reinterprets procedural precedent by simple majority, has drawn so much attention.
Suspending the House’s Rules
The House routinely uses “suspension of the rules” to move noncontroversial bills quickly. A motion to suspend the rules and pass a measure requires two-thirds of the members voting. Debate is capped at 40 minutes, and no floor amendments are allowed. A bill that fails under suspension can still come back through normal procedures later. The mechanism carries a large share of the bills the House passes each session, though it is generally reserved for measures with broad bipartisan support.
How the Two-Thirds Count Actually Works
For veto overrides, constitutional amendments, treaty ratification, impeachment conviction, and expulsion, the Constitution specifies two-thirds of the members present, assuming a quorum. A quorum in either chamber is a simple majority of the total membership. Absences lower the raw number of votes needed. If only 80 senators are present for a treaty vote, 54 votes suffice rather than the 67 required with all 100 senators in the chamber. Who is in the building on the day of the vote can matter as much as who supports the measure in the abstract.