AFTER HAGGLING for weeks over the terms of a "pay-as-you-go" provision that would help give a spendthrift Congress some fiscal backbone, House and Senate Republican negotiators have produced a measure that is essentially make-believe. It purports to require that tax cuts or spending increases be paid for with offsetting tax increases or spending cuts. It pretends to impose that rule for the next 10 years.

But it then provides, in the very same section, that the rule expires on April 15, setting the stage for a new tax-cutting spree next year. The rule applies only to the Senate. And it exempts $27.5 billion in tax cuts from this year's pay-go requirements. That is enough to extend for a year the popular tax provisions that are expiring: the $1,000 child tax credit, marriage penalty relief and expansion of the 10 percent income tax bracket. In other words, the Senate could extend those provisions without having to pay for them with spending cuts or tax hikes or having to amass the 60 votes needed to overcome the pay-go rule. Indeed, there is nothing in the resolution that would prevent lawmakers from using the $27.5 billion exempted from pay-go to enact less politically popular tax cuts by a simple majority vote, and then pass tax cuts for the middle class with 60 votes.

Fortunately, it doesn't look as if a majority of the Senate will agree to this irresponsible illusion of budget discipline when it comes up for a vote expected today. Credit is due to the Republican moderates who so far appear to be refusing to cave to party pressure -- Sens. Lincoln D. Chafee (R.I.), Susan Collins (Maine), John McCain (Ariz.) and Olympia J. Snowe (Maine) -- as well as to Democratic Sen. Ben Nelson (Neb.), who had been seen as a possible convert to the GOP position.

The business of passing appropriations bills can proceed, if a bit bumpily, in the absence of a budget resolution. So, too, can the debate over extending the tax cuts, and whether, as we believe, they ought to be paid for. "One year of pay-go is better than no year," said Senate Budget Committee Chairman Don Nickles (R-Okla.). That may be true, but one year of sham pay-go is far worse than having no budget agreement at all.