The long-planned Purple Line may never be built for lack of state funding, Montgomery County lawmakers have warned.

The 16-mile light rail system projected to run from Bethesda to New Carrollton is estimated to cost $1.9 billion -- money lawmakers say will be hard to raise. Another state transportation project, a bus rapid transit system planned for the I-270 corridor from Shady Grove to Clarksburg, known as the Corridor Cities Transitway, or CCT, is also in jeopardy. The CCT is expected to cost $828 million.

Though state officials hope to get as much as 50 percent of the costs of these projects from the federal government, the state is on the hook for the rest. And with the state's transportation trust fund lacking funds and state lawmakers having rejected proposals to replenish it this year, several Montgomery County lawmakers are nervous that the money will run out in 2015 and the projects will die.

"I'm very worried," said County Councilman George Leventhal, D-at large. "I've been told by many [state] legislators that [the Purple Line] isn't going to happen."

Leventhal has been among advocates of an increase in the state gasoline tax to fund transit. Though Maryland Gov. Martin O'Malley backed a 6 percent sales tax on gasoline in the spring's legislative session, the measure didn't have enough support to pass. For 20 years, Maryland has had a 23.5-cents-per-gallon gas tax, which is the same rate as in D.C. and a few cents higher than Virginia's 19.8-cents-per-gallon tax.

This week, Leventhal and other Montgomery County lawmakers have suggested the county stop waiting for the state to come up with the money for the projects and pass a gas tax of its own.

Several major planned development projects cannot move forward without transit, said County Councilwoman Nancy Floreen, D-at large, who chairs the council's Planning, Housing and Economic Development Committee. For example, Johns Hopkins University's plans for a research and development campus near Gaithersburg are contingent upon the CCT being built. And there are development plans in Chevy Chase that need the Purple Line.

"We will have far more modest redevelopment in those areas [without the CCT and the Purple Line]," Floreen said.

The county will also have a tougher time competing for jobs with Virginia without transit and the development it brings, Leventhal said. "We're stagnant. Meanwhile, Virginia is building the Silver Line, and Virginia is putting HOT lanes on the Beltway."

But Leventhal's concerns are premature, said Jack Cahalan, spokesman for the Maryland Department of Transportation. If the state doesn't pass a new tax to fund these projects in the 2013 or 2014 sessions, the state could turn to private developers to help support the cost of the projects.

"Three years is an eternity in the changing face of transportation funding," he said. "There's plenty of time to figure out how we get to the next step."