Elected leaders and top transportation officials from Maryland, Virginia and the District agreed in principle yesterday to find a dedicated source of money for the Metro transit system, but details of where they might find the funds are a long way off.

The agreement came at a meeting called to determine whether the region could take advantage of an offer from Rep. Thomas M. Davis III (R-Va.): Find a dedicated funding source, and Congress will give Metro $1.5 billion to take care of its major needs.

The leaders also agreed to begin the task of establishing an office of inspector general to oversee Metro, a measure also called for in Davis's bill.

Yet Davis's financial incentive does not guarantee that yesterday's agreement will yield regional cooperation. Many officials declined to offer specifics about how they would raise the needed revenue.

"It might be for negotiating purposes. It might be for ideological purposes. But at the end of the day, voters are not going to forgive excuses," said David F. Snyder, who chairs the Northern Virginia Transportation Authority. While yesterday's agreement keeps needed attention on the issue, he said, it does not go far enough. "The tough questions really remain."

The region's patchwork of oft-competing governments has had trouble dealing with major cross-boundary challenges such as traffic congestion.

Contrasting political systems, views and timing add complexity. Virginia Gov. Mark R. Warner (D) leaves office in January, and legislative elections are to be held in November, leaving many of the participants in any future agreement unknown. Pierce R. Homer, Virginia's secretary of transportation, acknowledged that uncertainty yesterday and said it is affecting "people's willingness to tackle this issue."

D.C. Mayor Anthony A. Williams (D) is leaving office at the end of next year as well.

Some regional tension was evident yesterday. One question that has sharpened debate is how much each jurisdiction's future Metro subsidy will be. D.C. officials keep raising the issue, while Maryland and Virginia officials warn that it could distract from the goal of capturing the offer in Davis's bill.

D.C. Council Chairman Linda W. Cropp (D) called the city's Metro contribution too burdensome and argued that the city has serious competing priorities. "The two largest tappers are Metro and education, and we need to do something," she said.

Cropp called Davis's bill an opportunity to grasp "an entirely different approach to funding Metro" but declined to say what that approach would be.

D.C. Council member Jim Graham (D-Ward 1) said he did not support a new sales tax for Metro funding, while Phil Mendelson (D-At Large) said he could support a slight increase. Council member Carol Schwartz (At Large) would not say what she supports, but as a Republican, she offered to lobby Maryland's Republican governor and Virginia's GOP-controlled legislature on the importance of coming up with dedicated revenue.

"I think we have done a lot so far, but to explicitly state what each jurisdiction would intend as their dedicated source, I think it's early yet," she said.

Davis said he was encouraged to see the region's leaders responding to his "$1.5 billion carrot" and beginning a difficult process.

"If it were that easy, it would have been done a long time ago. You have different political cultures, different rules. You have different funding formulas in each of the jurisdictions. So it's not surprising that they don't come to any quick consensus," Davis said.

He said the legislation was designed to offer maximum flexibility. "We leave it up to them. . . . They can cut other things, they can take it out of the growth in government, or they can come up with additional revenues."

Davis also said he hopes that Congress will agree to give Metro the full $1.5 billion. "The answer is, I think it will be there over the [10-year] period," he said, adding that he hopes the bill will become law within a year and a half.

There were indications that some officials are eager to move forward quickly.

Del. Carolyn J.B. Howard (D-Prince George's) said she and other members of the House Ways and Means Committee need a draft of Maryland's dedicated funding proposal within a few days so it can be approved for consideration by an Oct. 14 deadline.

But just what that legislation would say remains unclear. Maryland Secretary of Transportation Robert L. Flanagan said he is working with Davis's staff to determine what counts as dedicated funding. He would not say what he supports for the effort.

"The important thing here is not to emphasize quickness but to emphasize sure-footedness and determination," he said.

Gus Bauman, a District lawyer who was on a commission that recommended dedicating 0.5 percent of the sales tax from across the region to Metro, said he is not disturbed by the pace or lack of specifics.

"It doesn't have to be sales tax, and it doesn't have to be the same thing for all three," he said. "I have always known this is going to move at a snail's pace. But the snail often wins the race against the rabbit that collapses."