AS THE SUMMER holiday season winds down and local officials get back to work, one of the most urgent questions on their agendas should be how to capitalize on the prospect of $1.5 billion in federal funding for Metro. That alluring pile of cash, or rather the hope of it, is incorporated in a bill that Rep. Thomas M. Davis III (R-Va.) has introduced in the House Government Reform Committee, which he chairs. There is no question that Metro, with its aging infrastructure, mounting expenses and burgeoning ridership, badly needs the money. But a couple of questions have to be answered at the outset.

First, can Mr. Davis get his bill through Congress? He will certainly need the Bush administration's support. In particular, the bill requires the crucial backing of Joshua B. Bolten, director of the Office of Management and Budget and, as it happens, a native Washingtonian. The bill merits Mr. Bolten's support. Federal workers make up almost half of Metro's ridership, and the transit system could play a uniquely vital role in any regional emergency that might befall the Washington area.

The second question revolves around funding. Local officials must begin focusing on how to fulfill one of the bill's central components: that the region guarantee Metro a steady, earmarked source of funding. Nearly alone among the nation's major public transit systems, Metro has no guaranteed stream of funding and must scramble for money each year from the District, the two states and, in Virginia's case, Arlington and Fairfax counties and the city of Alexandria. That bizarre arrangement turns Metro into a beggar and compromises its long-term health. Mr. Davis's bill provides a badly needed incentive for the region's often competing jurisdictions to act in concert to trigger an important infusion of federal funding.

Already, D.C. Mayor Anthony A. Williams (D) has signaled that he is favorably disposed toward a 0.5 percent sales tax increase to fund Metro. That would be an important, constructive step, in line with the recommendations of a panel that studied Metro's long-term funding issues in the past year. It is less likely that a new tax would be adopted either in Virginia or Maryland, but officials in both states can and should begin studying which existing sources of revenue can be dedicated to Metro. Too often the barrier posed by the Potomac River has precluded regional cooperation. But with $1.5 billion on the table, who will be able to walk away empty-handed, explaining to voters that it was impossible to make a deal?