IT’S NOT THE RULES of the U.S. Senate that need fixing; it’s the partisan behavior and resistance to compromise.

Republicans in the Senate are contemplating ending the long-standing rule allowing filibusters, at least as far as judicial nominations are concerned. It now takes 60 votes to break a filibuster; the rules change would bring that down to a simple majority of 51. There now are 55 Republicans in the Senate. It what is supposed to be a great deliberative body focused on ideas and values, the math, sadly, is as basic as that.

Regarding the politics of this move, it’s worth noting that a majority of Americans responding to a Washington Post/ABC News poll believe that the filibuster should not be overturned. The U.S. Senate should not be run on polls, certainly. But this drive in the face of public opinion is a telltale sign that another force is pushing this.

This is a case of both extremes crushing the sensible middle. Neither party has been looking out for the common interest, which is supposed to be at the heart of lawmaking, in the fight over nominations. Republicans have backed themselves into a corner with the sky-high post-election expectations of their religious conservative wing. With this group pushing Republicans from the right, and special-interest lobbies on the left urging Democrats to give no ground, a collision course is set. Without these outside groups pressing them, Democrats and Republicans could work this out.

To defend this change, Republicans are advancing a valid argument: The filibuster is about giving a minority a chance to be heard, not absolute power to prevent a vote. But the filibuster is supposed to be a tool to push a compromise, too. It’s one of those devices that prods a legislative body to move toward consensus, when it is used judiciously.

The Democrats have sought a compromise on the disputed federal court nominations. They have offered to confirm some of those who were filibustered before, if a deal would preserve the current rules. Republicans have made a counteroffer.

This fight isn’t really about lower court nominations, of course. With Chief Justice William Rehnquist ailing, at least one Supreme Court seat is likely to become vacant soon. This is really the fight before the big fight, and promises an even bigger mess for the country.

But if this descent into partisanship continues, how will the Senate get anything of importance done? Republican senators, notably Lindsey Graham, want Democrats to join them on an ambitious rescue of Social Security. After such meltdowns over judicial nominees, how will any agreements across the aisle be made?

If Republicans want to govern effectively from their majority position, they will step back and accept a compromise: It would only improve their ability to govern. And Democrats must do more than just attempt to block endlessly; they must recognize the majority’s right to exert the influence that voters have conveyed.

The best way for both to do that: Make a deal on nominees, leave the filibuster intact, then try to come together as the deliberative body they are supposed to be. It is their duty to this divided nation.