Check out this article form Politico: "In the spring of 2005, I was one of the senators who banded together as the Gang of 14 to preserve the filibuster rule. We aimed to prevent the Republican majority from scrapping it on a simple majority vote, the “nuclear option.” The seven Republicans in the group agreed to vote against the nuclear option, if and when Republican Majority Leader Bill Frist called for a vote. The seven Democrats agreed to vote against their party’s filibusters, unless “extraordinary circumstances” were in play.Read more