cloture - The only procedure by which the Senate can vote to place a time limit on consideration of a bill or other matter, and thereby overcome a filibuster. Under the cloture rule (Rule XXII), the Senate may limit consideration of a pending matter to 30 additional hours, but only by vote of three-fifths of the full Senate, normally 60 votes.
http://www.freerepublic.com/focus/f-news/2367061/posts
The new version of the cloture rule, which has remained in place since 1975, makes it considerably easier for the Senate majority to invoke cloture. This has considerably strengthened the power of the majority, and allowed it to pass many bills that would otherwise have been filibustered. (The Democratic Party had held a two-thirds majority in the 89th Congress of 1965, but regional divisions among Democrats meant that many filibusters were invoked by Southern Democrats against civil rights bills supported by the Northern wing of the party.) Some senators wanted to reduce it to a simple majority (51 out of 100) but this was rejected, as it would greatly diminish the ability of the minority to check the majority.