A legislator who holds the floor to delay or block a vote is conducting a filibuster. The tactic exploits rules that allow extended debate unless a supermajority votes to end it.

In the United States Senate the filibuster has become a routine instrument of minority influence. Continuous speech was once required; modern practice often relies on the mere threat of prolonged debate. Cloture rules set the threshold for cutting off discussion. Defenders call the filibuster a protection for minority rights and deliberation; critics call it a recipe for gridlock that frustrates majority rule.

Other legislatures have adopted or rejected similar devices. Reform proposals periodically surface when the tactic frustrates a newly elected majority. The existence of the filibuster shapes legislative strategy, encouraging broader coalitions or deterring the introduction of controversial measures.

A single determined senator can still force the chamber to expend time and political capital.