IN HIS STATE of the State speech a few weeks ago, Maryland Gov. Martin O’Malley (D) pointed to the “worst traffic congestion in the country” without outlining a plan to relieve it. There was tactical logic to the governor’s reticence: Last year, his bold proposal to raise hundreds of millions of dollars for roads and rail through a sales tax on gasoline flopped in the legislature. Better, perhaps, to stand back and negotiate quietly this year.

Meetings have taken place in Annapolis, and the Senate president has introduced his own plan. But nearly halfway through Maryland’s three-month legislative session, the tangible results are nil. The state’s transportation system, meanwhile, is fast running out of money for new projects. It’s time for Mr. O’Malley to lead.

No doubt, there is political peril in staking out a revenue-raising proposal whose effects may include higher gasoline prices. In a fragile recovery, there’s not much support for that among lawmakers — and possibly even less among the driving public.

Still, since taking office in 2007, Mr. O’Malley has twice led the way on raising taxes — once to fix the long-term structural deficit he inherited and again to maintain state services in the wake of the Great Recession. In those fights, it may have been too much to also plug a looming gap in transportation funding. But with cash for new road and rail projects forecast to evaporate by 2017, the issue cannot be deferred indefinitely.

To his credit, Thomas V. Mike Miller Jr. (D-Calvert), the powerful state Senate president, has kept the transportation ball rolling. Mr. Miller introduced a bill that would impose a 3 percent sales surtax on gas — half of what Mr. O’Malley proposed last year. In addition to raising new funds, the surtax would keep pace with inflation, unlike the flat 23.5-cents-per-gallon tax that has been in place for more than 20 years.

Mr. Miller’s blueprint also would establish regional authorities empowered to increase local property taxes for transit projects such as the Purple Line in the Washington region. It envisions more money if county governments agree to raise gas taxes in their individual jurisdictions.

Some of those ideas are plainly sensible, especially the sales surtax on gas. Others may stoke tensions between urban and rural areas or fail to attract political support. The main purpose of Mr. Miller’s bill is to keep the debate alive, awaiting gubernatorial intercession.

The governor has put his shoulder into several battles in the past couple of years: same-sex marriage; tuition subsidies for undocumented students who graduate from state high schools; offshore wind energy; and ending the death penalty. Even in what amounts to a one-party state, those were tough fights, and he won national plaudits for taking them on.

The only way to win hundreds of millions of dollars in new transportation funding is with a similarly resolute effort from Mr. O’Malley. With statewide elections complicating things next year, the time for a push on transportation is now.