Washington-area governments on Wednesday endorsed the goal of dedicated funding for Metro but could not agree on key questions, including how much money the agency needs or how to raise it.

The board of the Metropolitan Washington Council of Governments (COG) unanimously agreed on a “statement of principles” to guide the region as it wrestles with what Metro General Manager Paul J. Wiedefeld says is the increasingly urgent need to rescue the transit system’s ­finances. But internal disputes led the board to balk at endorsing specific recommendations from a COG technical panel in April that called for a uniform 1 percent regional sales tax to raise $650 million a year to cover capital and maintenance costs at the transit agency.

The resolution called dedicated funding, a bondable funding stream that would significantly enhance Metro’s long-term borrowing abilities, the “optimal way” to fulfill the system’s capital needs. It also embraced elements of Wiedefeld’s proposal — including capping at 3 percent the annual increase in subsidies from the jurisdictions that fund Metro and retooling the agency without rewriting its governing compact.

Loudoun County Supervisor Matthew F. Letourneau (R-Dulles­), who is COG’s vice chairman, fought successfully to include language in the resolution that would leave the door open for reopening the compact.

Wiedefeld, who presented his financial road map for the system in April, has called for $15.5 billion over 10 years for capital needs — including $500 million in new, annual dedicated funding — and a slew of concessions from Metro’s unions.

Wiedefeld, who attended Wednesday’s meeting, hailed the resolution as a sign of progress but acknowledged the significant hurdles his plan faces. He has asked that dedicated funding be in place by July 1, 2018 — in time for the 2019 fiscal year.

“I mean, I think across the board . . . people are coming to the table and saying that we’ve got to deal with this,” Wiedefeld said. “My only concern is . . . that we have to move and we have to move fairly quickly on this, or we will be in a pretty difficult situation going into the [2019 fiscal] budget.”

Wednesday’s resolution made clear that the region’s officials are not ready to accept Wiedefeld’s financial recommendations at face value. Besides the COG analysis and Wiedefeld’s plan, a study from a panel headed by former U.S. transportation secretary Ray LaHood is forthcoming. The LaHood panel, convened by Virginia Gov. Terry McAuliffe (D), is expected to lay out Metro’s long-term governance and financial needs. A COG strategy group headed by Fairfax County Board of Supervisors Chairman Sharon Bulova (D) has been engaged in conversations with LaHood ahead of the study and is expected to make more concrete recommendations in the coming months.

Despite the limitations of the endorsement, Bulova said, Wednesday’s resolution was a step in the right direction.

“I think an important part of what was passed is that additional funding is needed and that it needs to be bondable, and it doesn’t have to be a sales tax, although it could be a sales tax, or it could be a blending of other revenues,” Bulova said.

“But the important thing is whatever color the money is, it needs to be predictable, it needs to be bondable, and it needs to pass muster, essentially, with the [bond] rating agencies.”

Metro, funded through a combination of jurisdictional subsidies and federal grants, stands alone among the nation’s major subways in its lack of a significant source of dedicated funding. D.C. officials have called for a regionwide sales tax, but the proposal is a nonstarter for some Northern Virginia Republicans. And last week, a rift became evident in suburban Maryland when the Prince George’s County’s representative to the Metro board declined to endorse Wiedefeld’s plan, saying it required more study, and raised particular concerns over the impact on the labor force.

COG’s resolution was similar to one approved by the Metro board last week and another approved by the Northern Virginia Transportation Commission — both endorsing the spirit of Wiedefeld’s proposal.

“The heavy lifting hasn’t begun,” D.C. Council Chairman Phil Mendelson (D) said after Wednesday’s vote. “It’s going to have to begin soon.”

Though officials have not explicitly endorsed the specifics of his plan nearly two months after its unveiling, Wiedefeld said the discussion has advanced significantly.

“Think of where we were a year ago; this was not part of the public discussion,” Wiedefeld said. “We did not have detailed thoughts out there from a number of groups. None of that was in existence. It was more about the organization itself. I think we’re moving beyond that and we’re focusing on the real issues, and I’m very encouraged by that.”

Metro Board Chairman Jack Evans was realistic about the implications of the COG resolution.

“There’s not a lot of profile in courage in this statement,” Evans said before the vote. He said he was puzzled by the decision to omit a dollar figure needed for the agency, considering the analysis by COG’s technical panel. On the other hand, he said, he was pleased to see that COG was endorsing a proposal that included the words “dedicated funding source.”

“I think that’s a huge achievement,” said Evans, who also is a member of the D.C. Council.

Maryland Del. Marc A. Korman (D) was optimistic about the trajectory of the funding discussion in light of Wednesday’s vote but said significant work remains.

“I hope we’re on a road to dedicated funding by this time next year. But I also think dedicated funding alone is not the answer,” he said. “The problem with Metro is not just funding. Money helps. I want them to have dedicated funding, but there are other issues there with the management, with the governance, that need to be addressed.”

Robert McCartney contributed to this report.