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."
From Christinia Crippe's story for the Hawk Eye:
"I think, if anything, this health care debate is showing the dangers of unlimited filibuster," Harkin said Thursday during a conference call with reporters. "I think there's a reason for slowing things down ... and getting the public aware of what's happening and maybe even to change public sentiment, but not to just absolutely stop something."
Harkin noted with interest that his original legislation was cosponsored by Sen. Joe Lieberman, I-Conn., who has been threatening to filibuster the legislation.
Harkin's idea would preserve means for senators to slow down debate on a bill without imposing a 60-vote threshold for all bills in the Senate:
"Today, in the age of instant news and Internet and rapid travel -- you can get from anywhere to here within a day or a few hours -- the initial reasons for the filibuster kind of fall by the wayside, and now it's got into an abusive situation," Harkin said.
He and the constitutional scholars agree that the intention was never to hold up legislation entirely.
To keep the spirit of slowing down legislation, though, Harkin's proposal back in 1995 would have kept the 60-vote rule for the first vote but lessening the number required in subsequent votes.
He said for instance if 60 senators could not agree to end debate, it would carry on for another week or so and then the number of votes required to end debate would drop by three. Harkin said it would carry on this way until it reached a simple majority of 51 votes.
"You could hold something up for maybe a month, but then, finally you'd come down to 51 votes and a majority would be able to pass," Harkin said. "I may revive that. I pushed it very hard at one time and then things kind of got a little better."
Harkin is right to call attention to the current abuse of the filibuster, and his approach makes a lot of sense. Unfortunately, it will be an uphill battle to get a critical mass of senators to agree to change the rules. Harkin's 1995 effort was tabled by a vote of 76 to 19.