The Constitution does not contain a supermajority requirement for ordinary legislation to pass the Senate, but the filibuster has evolved into a means to kill any bill unless 60 senators support it.

The current use of the filibuster is not “traditional.” This memo from December 1964 shows that no one imagined Medicare would need more than a simple majority in the Senate. There was no expectation that Lyndon Johnson’s reform efforts would fail if Medicare couldn’t command a filibuster-proof majority.

Senator Tom Harkin tried to change Senate rules on the filibuster in 1995, and the Burlington Hawk Eye reports that he may try again, “Given what he sees as the abuse of power by a couple members of his own party whom he said are threatening to join the minority party if their every demand is not met.”