Northern Virginia efforts to win new funds for the Metro transit system collapsed today when a freshman delegate inadvertently failed to vote on a gasoline-tax proposal.

The proposal, which would have provided $13.2 million in funds for the financially strapped Metro, was defeated on a 49-to-49 vote in the House of Delegates. Legislators said the action will make it extremely unlikely that Northern Virginians will be able to win increased financial support for their area's transit system during the current legislative session.

At fault, legislators said, was freshman Del. G.C. Jennings (D-Marion), who had intended to vote for the tax measure, but apparently failed to flick his voting lever. "Of course I'm embarrassed; I feel like I let them down," Jennings said.

"We've got no more leverage," said Del. Warren G. Stambaugh (D-Arlington) after the vote. "All of our leverage is gone."

Today's decision, on a $114 million compromise gasoline-tax measure, followed two days of bitter floor debate over the state's highway fund allocation formula and cast doubt over prospects for an increase in Virginia's 11-cent retail gasoline tax. The state's highway department and Gov. Charles S. Robb have said some kind of new highway revenue measure is necessary to cover a projected $360 million, two-year deficit in road construction projects.

Northern Virginians were hoping to salvage some $13.3 million annually for Metro's annual operating deficit through their proposal for a 4 cent-a-gallon increase in the state's gasoline tax. But the House voted instead, by 52 to 47, to approve an increase of $45 million in licensing fees that earmarked no funds for Metro.

A loose coalition of Northern Virginians and rural and suburban legislators had designed their package to offer something for everyone, with large chunks of highway money set aside for each legislator's district. In addition to the Metro money, there was $17.1 million to pave secondary roads in rural districts. Another $17.1 million would have been spent to build roads in the state's growing suburbs.

The proposal ran into a wall of opposition from conservative and urban legislators, who charged that members of the coalition were taking advantage of the state's highway funding troubles. "I have seen pork barrel in my life, and this is a beaut," said House Majority Leader Thomas Moss (D-Norfolk). "Everybody gets a piece of the pie, but that doesn't make the pie any more palatable."

Jennings, one of the Southwest Virginians in the coalition, said he failed to notice his mistake until after Speaker A.L. Philpott had announced the 49-49 tie. Philpott refused to let Jennings cast his vote then, citing a House rule that prohibits members from changing sides after a vote if the change will reverse the outcome of an issue.

Today's vote sends the $45 million licensing package to the Senate, which earlier passed a $263 million package of highway user taxes that includes a 3 percent tax on wholesale gasoline sales. The Senate package, which would add 4 cents to pump prices, does not include new money for Metro.

Sen. Hunter B. Andrews said today that the Senate Finance Committee will likely insist on its own bill, forcing a conference committee to hammer out a compromise in the final days of the session. Because neither House nor Senate proposal carries any Metro funding, it is considered unlikely that funds for the transit system can be attached to either measure.

Northern Virginia's legislators have vowed to block any gasoline tax increase that doesn't include funding for Metro, and earlier this week helped to kill a 3 cents-a-gallon tax increase by a 67-to-26 vote. "I hope under these circumstances there'll just be none, and the governor and the others will be out in the cold," said Stambaugh.

Gov. Robb, who has been criticized for not offering leadership in the gasoline tax debate, said he was not at all disturbed by today's outcome. "What the House did was exactly what I asked them to do," said the governor at an afternoon press conference. "And that is, get a vehicle a tax measure over to the Senate side."

Robb said he expected that some gasoline tax to raise critically needed revenues for the highway department will eventually come out of a conference committee on the bill. Unlike Stambaugh and other Northern Virginia legislators, Robb also said he believes the final version may also include Metro money. "Obviously, I'm from Northern Virginia and I share their concerns and I'm not willing to abandon the legislative needs and concerns of that area."

Northern Virginia motorists are already paying a 2 percent retail gasoline tax to support Metro's operating deficit, and face another 2 percent increase in the tax July 1.

Legislators from the Washington suburbs said the need for additional Metro money comes after federal officials concluded the tax has failed to be the "stable and reliable" funding source for Northern Virginia's share of the Metro operating deficit. Unless such a source is found, U.S. Transportation Secretary Drew Lewis recently warned that $100 million in federal funding for Metro construction could be in jeopardy.