WASHINGTON — The Supreme Court nomination of Judge Neil M. Gorsuch is now going to the Senate floor. The Senate minority leader, Chuck Schumer of New York, has pledged to lead Democrats in a filibuster of the nomination. If he does, the majority leader, Mitch McConnell of Kentucky, has vowed to change Senate rules to clear the way for Judge Gorsuch. The potential showdown has raised interest in the peculiar Senate filibuster rule.

What is a filibuster?

A filibuster is an effort by a minority of lawmakers to delay or block the Senate from voting on a bill or a confirmation. By exploiting the chamber’s rules for full debate on an issue, the minority can indefinitely obstruct something that has majority support. According to the Senate Historical Office, the term traces back to a Dutch word meaning “pirate.”

How does it work?

The Senate generally operates by unanimous consent. If any senators refuse to consent to holding an up-or-down vote on Judge Gorsuch’s nomination, the Senate has to decide whether to overrule them. It would do so by holding a “cloture” vote on whether to end debate and proceed to a final vote. It takes 60 votes to invoke cloture, so 41 senators can indefinitely block a confirmation by refusing to vote for cloture.