Top local government and business groups said Monday that they will press the Virginia and Maryland legislatures in early 2018 to approve a regional tax or other funding mechanism for Metro to help pay the steep costs of renovating the long-neglected system.

The Metropolitan Washington Council of Governments and Greater Washington Board of Trade set the target date at the end of a forum where heads of other major transit agencies stressed that creating a dedicated source of revenue was essential for a system to succeed.

The transit chiefs — from New York, Chicago, Atlanta and elsewhere — also said they had faced many of the same challenges as Metro. They said the Washington region’s system could recover from chronic problems with safety and reliability if it were given good leadership, together with sufficient time and money.

Metro is the only major U.S. transit system that does not receive a substantial amount of revenue from a reliable funding stream, such as a regionwide sales tax. Decades of efforts to set up such a source have failed partly because Virginia, Maryland and the District couldn’t agree on a plan, and partly because local politicians were loathe to raise taxes.

The year-long Metrorail rehabilitation plan includes 15 projects that will require the longest stretches of single-tracking and station shutdowns.

The lack of revenue has contributed to Metro’s failure in recent years to keep up with investments needed to maintain the system in a state of good repair.

Alex Barron of the Imperial College in London, a leading international transit expert, told the forum that Metro’s rate of capital spending from 2003 to 2014 was the lowest among eight major U.S. transit systems.

The new initiative to create a dedicated funding source is certain to face strong opposition, especially in Virginia, where leaders of the Republican-controlled General Assembly have already said such a plan was a non-starter.

But COG and the Board of Trade hope to overcome the obstacles with what amounts to a two-part plan. First, they want to set firm benchmarks for improving Metro’s performance on safety, reliability and financial management. Second, they want to convince legislators outside the metropolitan area that fixing the subway is vital to prosperity in the Washington region, which is the economic engine for both Virginia and Maryland.

COG Chairman Roger Berliner, who also is a Montgomery County Council member (D-Potomac-Bethesda), hopes to dub the proposal the “Culpeper plan,” referring to the Virginia town 70 miles southwest of Washington.

“How do we convince a rural legislator in Culpeper that funding Metro is in his interest, is in his state’s interest?” Berliner asked rhetorically. “We need to make that case.”

Having trouble maneuvering around Metro's 10-month maintenance overhaul? Well here is a guide to help riders find the perfect alternative. (Ashleigh Joplin/The Washington Post)

COG and the Board of Trade hope to agree on a regional plan by the end of this year for a dedicated revenue source. But they think it would be too rushed to try to sell such a plan to skeptical legislators in the General Assembly sessions starting in Richmond and Annapolis in January.

Instead, they plan to devote 2017 to lobbying the legislatures to lay the groundwork to make the pitch in 2018.

The District also would have to approve such a plan, but is expected to be supportive.

The forum, attended by about 80 officials, business executives and transportation advocates, was the second in a series organized by COG and the Board of Trade to address the recent surge of public concern about Metro.

The group heard from heads of other cities’ transit agencies that their riders were used to dealing with service cutbacks of the sort that Metro is currently experiencing to allow for critical maintenance and repairs.

Metro “is going through something that systems like Chicago and New York have been going through for decades,” said Dorval Carter Jr., president of the Chicago Transit Authority.

The Washington area “got kind of spoiled” in the past, when service disruptions were avoided at the cost of neglecting maintenance.

He and others also stressed the importance of having a dedicated revenue source in order to make plans for the future and minimize political fights over funding.

The heads of agencies in Atlanta and Toronto said their systems had recovered from low points like the one to which Metro has sunk. They said it was important first to restore public confidence through small measures such as providing clean trains or otherwise improving customers’ experience.

Keith Parker, general manager of Atlanta’s system, said he helped restore riders’ confidence by proclaiming a policy that he called “no knucklehead behavior.” That included banning panhandling, loud music and roughhousing on the system. The agency increased police presence and suspended 8,000 people from using transit when they violated the rules.

Although Metro’s financial woes are partly of its own making, because of internal mismanagement, the system is widely seen as short of funds even after accounting for its missteps and inefficiencies.

The Metro board chairman, Jack Evans, who also is a D.C. Council member (D-Ward 2), told the forum of the “three numbers” that he says describe Metro’s needs—which he has gotten in the habit of repeating at every public event: $18 billion in the next 10 years for investment; $300 million a year from the federal government for operations; and $2.5 billion to cover an unfunded pension fund liability.

Evans would like a dedicated funding source from the region to provide $1 billion a year to cover the investment need. But Republican legislators in Virginia have said they would oppose increasing spending by even a penny, on grounds that taxpayers are already overburdened and Metro needs to reduce costs.

Former congressman Tom Davis, a moderate Republican who led a successful fight to procure a temporary federal funding plan for Metro, warned the group that GOP political opposition would be strong.

“In Virginia, I don’t think there’s a single Republican legislator with a Metro station,” Davis said.

Davis said the only potentially effective argument would be that Metro is necessary for the economic vitality of the Northern Virginia suburbs, which in turn generate a huge chunk of tax revenue for the rest of the state.