Metro took a first step yesterday toward extending subway hours past midnight, but top officials argued over how late to go and whether Washington's trains can serve both night-owl clubgoers and workday commuters.

A budget committee of Metro directors voted 4 to 2 to extend the subway's weekend closing hours from midnight to 1 a.m. for an eight-month trial.

Elected officials and a hodgepodge of unlikely allies had pushed for a 2 a.m. closing. The Montgomery County Chamber of Commerce joined forces with the Sierra Club, and Mothers Against Drunk Driving linked up with 12,000 listeners of a local rock radio station.

But yesterday's debate exposed a sharp split between Metro board members who said that Metro must expand its ridership base and those who argued that later hours would strain the transit system's resources and shortchange its most loyal customer, the daily commuter.

It is time Metro served "a younger rider, who is out on the town, probably could be drinking, a rider that is every bit as entitled to service as our 55-year-old lawyer who comes in during the day and goes home at night," said Jim Graham, a Metro board member who proposed that subway service be extended from midnight to 2 a.m. on Saturdays and Sundays.

Graham, a D.C. Council member who represents the restaurant and club neighborhoods of U Street and Adams-Morgan, said public support for a 2 a.m. closing is "very strong and virtually unanimous."

But board member John Davey, who represents Prince George's County, said Metro needs to spend resources to improve daily service before it can afford the "luxury" of late-night trains. Davey said he was troubled by recent service problems on the Red Line and is still cringing from a rider revolt in the spring, when frustrated passengers at Metro Center refused to disembark a train that was being taken out of service.

Extending service past midnight shortens the "maintenance window"--the hours when trains are idle and maintenance workers can fix problems on the rails or prevent new ones from developing.

"Our highest priority has to be the riders who use our system every day," Davey said. "We owe it to our daily riders to provide the best possible reliable service before we go extending service."

The fate of the compromise plan remains uncertain. The two votes cast against the proposal yesterday came from Maryland's representatives on the budget committee, and the plan needs at least one Maryland vote to receive final approval when the full Metro board considers it next Thursday.

Metro has the earliest closing time among the nation's major transit systems. Extending the weekend hours until 2 a.m. would mean an additional $3.9 million in annual operating costs and would generate 7,200 new trips each night, according to Metro. Extending the hours until 1 a.m. would cost $2.1 million in annual operating costs and generate 4,600 new trips each night. Under both scenarios, Metro would have to spend $1.1 million in one-time capital costs. The extra revenue would cover about one-third of the cost of the expanded service.

"I hope that the Maryland representatives can find a way to work with all of us who want this to happen," said state Del. William A. Bronrott (D-Montgomery), who wrote a letter that was signed by 28 other Maryland lawmakers to Metro's board of directors asking for a 2 a.m. closing.

Davey proposed extending weekend hours to 1 a.m. for eight months but having the funding expire at the end of the experiment instead of building it into future Metro budgets.

After Davey failed to get support for his budgeting proposal, he and the other Maryland member of the budget committee, Cleatus E. Barnett, of Montgomery County, voted against the 1 a.m. compromise.

Davey said he was confident that he and other board members will be able to hammer out a new agreement by next week's vote.

Graham and others argued that Davey's stipulations were "hamstringing" the project. "They're hobbling what should be a great idea," Graham said. "Putting these restrictions on funding is a way to discourage its success."

Budget committee member Chris Zimmerman, of Arlington County, said extending closing to 1 a.m. instead of 2 a.m. does not accurately test the market for late-night train service. "If you run until 1 a.m., people may think, 'I don't want to run out at 12:30 to catch Metro, I'll just take my car.' I'd like for this to really have a chance to succeed. It makes more sense to run it to 2 a.m," said Zimmerman, a member of the Arlington County Board.

Montgomery County Executive Douglas M. Duncan (D), who had been lobbying for a 2 a.m. extension, said he was willing to accept a 1 a.m. closing for now.

"It's not the full two hours, but it is one extra hour," Duncan said, adding that he believes a compromise will be reached in time for next week's vote. "It's very positive that we're going to get any extension, and we'll keep working after this to get to 2 a.m."