THE DRIVE to force the calling of a constitutional convention to consider an amendment that purports to require a balanced federal budget ran into another roadblock this week. The Montana Supreme Court followed its counterpart in California and removed an initiative measure from the ballot that was intended to force the legislature to call for such a convention.

You might think this decision would please conservatives who call themselves strict constructionists: the Constitution says that a convention should be called on application of legislatures, and the Montana court based its decision on the common- sense proposition that the voters are not a legislature. But, as you might expect, the amendment's backers are frothing at this latest frustration of what they see as the popular will. People who would risk rewriting the entire Constitution are not going to let themselves be distracted by what the Constitution actually says.

The California and Montana decisions, plus the refusal of the Michigan House of Representatives to vote a call for a convention mean that the drive for a constitutional convention is currently stalled. But it is no time for opponents of this desperate move to relax. If 34 legislatures call for a convention, Congress is bound to call one; and 32 legislatures have already done so. True, they've spoken over an extended number of years and in different wording; and so a persuasive argument can be made that Congress would not be bound by such non-contemporaneous and non-identical resolutions.

But why reach that issue? Why divert attention from the difficult issues of the day to arcane constitutional matters? Why put at risk the basic constitutional provisions that have served the United States so well? People who think a balanced budget is so desirable should do something that no serious figure has done lately -- come forward with one, and urge Congress to pass it. Until that happens -- and don't hold your breath -- the attempt to bludgeon the legislatures to summon a constitutional convention to pass this will o' the wisp amendment must be considered a cheap political ploy.