SO MUCH for Gov. John Dalton's ideas about a gasoline tax; unless the state Senate exhumes the remains of these once-great plans from the House graveyard, the transportation projects he sought to finance can be forgotten for the year. If constituents don't like the conditions of their highways over the coming months, they can blame the 10 members of the House Finance Committee who opposed the governor's proposal even after they stripped it down from a four-cents-a-gallon increase to two cents. But before everybody pulls away from the table, Northern Virginia still has some critical tax business to conduct in the legislature.

There is the other important proposal -- to raise the gas tax only in Northern Virginia. This measure, which calls for a 4 percent tax, is before the Senate, where its prospects are unclear -- which is the way the powers in Richmond prefer to keep things like this until the last possible confusing minutes of a session. There is "speculation" that some of Gov. Dalton's supporters in the Senate might indeed tack some kind of statewide tax amendment to the Northern Virginia bill -- which would be fine if it didn't just tempt the House to kill the whole thing in conference.

At this point, the Northern Virginia tax needs the undivided attention and support of every member of Northern Virginia's delegation to Richmond. The reason, in a word, is Metro. The "must" mission this year is to bring back a state-approved plan for providing the money necessary to meet federal requirements for subway financing. Gov. Dalton tried to help and came up short; it is now up to he lawmakers themselves to recognize and resolve the transportation problem that remains. It is not too much for a region to ask the legislature for permission to tax itself -- when the purpose happens to be a vital part of the entire state's transportation system. But successful pursuit of that permission will require an alert and determined delegation that does not succumb to internal bickering.