The Union Station Metro stop on April 4. (Mandel Ngan/Agence France-Presse via Getty Images)

METRO’S DIRE financial predicament has been apparent for years, even as local elected officials chose to look the other way, thereby hastening its spiraling safety, service and maintenance problems. Now the chief solution to the transit system’s financial problems is also crystal clear, if only those same politicians have the spine to adopt it.

Metro needs what every other major transit system in the United States has and takes for granted: a steady source of earmarked funding, not subject to the political vagaries of annual debate within and among its array of stakeholders. That’s been obvious for years. Yet, in 2005, when the Metropolitan Washington Council of Governments recommended a half-cent-per-dollar regionwide sales tax to meet Metro’s needs — for modern trains, new rails, enhanced systems and other capital requirements — elected officials averted their eyes and enabled the system’s accelerated senescence.

The result is painfully familiar: constant breakdowns and delays; ever-rising fares; and regular safety lapses, including lethal ones. Make no mistake: The current SafeTrack maintenance surge is a stopgap to avoid imminent disaster, not a program to establish a sustainable state of good repair.

Metro General Manager Paul J. Wiedefeld says the system’s infrastructure needs in the coming decade will cost $25 billion, although he says it could get away with a bare minimum of $15.5 billion. There are various methods of raising that revenue, and keeping it flowing. Most are broadly unpopular, with one exception: a regionwide sales tax.

Recent polls in Virginia (by The Post and George Mason University’s Schar School of Policy and Government) and Maryland (by The Post, in conjunction with the University of Maryland) yielded similar results. In both states, respondents disliked raising general taxes, property taxes or taxes on buildings and land around Metro stations. However, they disliked further service cuts and fare hikes on Metro even more. The one solution that generated majority support in both polls was a regional sales tax.

The polls did not ask about specific taxing levels, but there’s no secret about the approximate scale of funding that is needed. A 1 percent tax on sales in the District and suburban localities in Northern Virginia and Maryland would generate an estimated $650 million annually, which, leveraged in the bond market, would more or less cover the system’s needs in the coming decade.

Despite the poll results, enacting a regional sales tax — and coordinating it among the three jurisdictions — will be a very heavy lift. Republicans who control the legislature in Richmond would have to give their assent to Northern Virginia taxing itself, and Maryland Gov. Larry Hogan (R), whose enthusiasm for mass transit is limited, would also have to sign off. Locally, some myopic GOP elected officials grumble that Metro should spend its money more wisely before asking for new revenue — as if the steep staff cuts, fare increases and efficiencies pioneered in recent years by Mr. Wiedefeld were fake news.

Metro is not a lost cause. But to revive it, politicians will need exactly the sort of resolve they haven’t mustered in the past.