The filibuster, a Senate procedural tactic frequently used by Republicans to block legislation and nominees favored by President Obama, met its match in November, when Senate Democrats voted to deploy the so-called “nuclear option” to neuter its power.
The nuclear or constitutional option, is a parliamentary procedure that allows the U.S. Senate to override a rule or precedent by majority vote. The presiding officer of the United States Senate rules that the validity of a Senate rule or precedent is a constitutional question. He immediately puts the issue to the full Senate, which decides by majority vote. The procedure thus allows the Senate to decide any issue by majority vote, even though the rules of the Senate specify that ending a filibuster requires the consent of 60 senators (out of 100) for legislation, 67 for amending a Senate rule. The name is an analogy to nuclear weapons being the most extreme option in warfare.