A powerful constitutional, historical and procedural case can be made for doing away with the Senate filibuster. We doubt it’s going to happen, but Senate rules certainly ought to be modified — along with the behavior of Senators of both parties.

The historical case was passionately argued on the Senate floor Jan. 5 by Sen. Tom Harkin of Iowa, who has sponsored legislation that would incrementally reduce the number of votes it takes to end debate from the present 60 down to 51 over a nine-day period.

As the Iowa Democrat pointed out, the Constitution stipulates five categories of activity requiring supermajorities — treaty ratification, veto overrides, impeachment, constitutional amendments and expulsion of a Member — implying that all other business would be conducted by majority vote.

Early Congresses had no filibuster. It was first adopted in 1806 but rarely used. The rule providing for a supermajority to invoke cloture was adopted in 1917. From then until 1969, there was fewer than one filibuster per year, even through the civil rights days.

But since then, as Harkin said, the number has skyrocketed and both parties have used it as a technique for obstruction. In the 110th Congress, there were 139 cloture votes; in the 111th, 136.

Nowadays it requires 60 votes to pass any significant legislation — and even measures with huge support get held up for reasons of strategy, logrolling or politics.

The Senate is due to vote this week on new rules, and some Democrats and outsiders are urging that the rules package be adopted by a simple majority, not the two-thirds normally required to change rules.

When Republicans talked about doing this in 2005, it was called “the nuclear option,” one that would result in massive retaliation. The same might happen if Democrats try it this year.

What argues for keeping the filibuster is tradition — and that’s not to be sneezed at. Critics claim that the filibuster leads to “tyranny by the minority,” but minority influence is what makes the Senate different from the House, where “tyranny by the majority” is often the rule.

We guess the Harkin proposal will go down to defeat, but other good ideas should not: an end to “secret holds,” requiring Senators denying unanimous consent to identify themselves and a move to hold one cloture vote per bill, eliminating filibusters on the motion to proceed and on amendments.

Moreover, as Sens. Tom Udall (D-N.M.) and Jeff Merkley (D-Ore.) have proposed in their reform package, those who wish to filibuster should be required to hold the floor — “Mr. Smith Goes to Washington” style — rather than have the mere threat of endless debate carry the full weight of the deed itself. In addition, their proposal would guarantee the minority party at least three amendments per bill.

Also in the works are measures to speed the confirmation process of administration nominees. Sen. Lamar Alexander (Tenn.), the Republicans’ chief rules negotiator, says that the Senate “needs behavior change, not rules change.” We say it needs both.