The filibuster and cloture
The answer
Most people think a bill needs 60 votes to pass the Senate. It doesn't, it needs a simple majority, 51 votes, or 50 plus the Vice President. What usually needs 60 votes is ending debate and forcing that final vote at all. That procedural step, called cloture, is the filibuster's real mechanism. A minority of just 41 senators can keep debate open indefinitely and block a vote from ever happening, without a single senator having to hold the floor and talk.
How it actually works
Senate Rule XXII, adopted in 1917, allows any senator to keep debate on a bill open by objecting to a request to move to a vote. To end that debate, a senator files a written cloture petition signed by at least 16 senators. Under the rule, the petition must ripen, meaning the Senate must wait until one hour after convening on the second calendar day after filing, before voting on cloture itself.1 Cloture on most legislation requires three-fifths of senators duly chosen and sworn, 60 votes if all 100 seats are filled.2 If cloture succeeds, a 30-hour cap on further debate kicks in and a final vote must occur. If it fails, the bill is effectively dead unless leadership tries again or attaches it to something else.
Example: in November 2025, during the fight over FY2026 government funding, competing Republican and Democratic short-term funding proposals each failed cloture in the Senate, 44-48 and 47-45, neither reaching 60. That failure, not a floor vote against the bills, is what plunged the government into the 43-day shutdown that ran until November 12, 2025.
Who holds the power
Any single senator can object and force the cloture threshold into play. Leadership decides whether and when to file a cloture petition and burn floor time on the ripening delay. A committed minority of 41 senators can sustain a filibuster indefinitely. The Senate majority can change the threshold for specific categories of business: judicial and executive nominations now require only a simple majority for cloture (changed in 2013), as do Supreme Court nominations (changed in 2017). Both changes were achieved by the nuclear option, a majority vote reinterpreting the rule rather than the two-thirds vote normally needed to amend Senate rules.
Budget reconciliation bills are explicitly exempt from the 60-vote cloture requirement, which is why major tax and spending packages increasingly move through reconciliation instead of ordinary legislation.
Where you come in
See the guide on how to contact your member of Congress to ask a senator's position on a cloture vote before it happens.
Related
Glossary: cloture, filibuster, nuclear option
See also the explainer on reconciliation.