WASHINGTON – Drivers will soon pay more at the pump in Maryland, thanks to a new gas tax. But even that won’t raise enough dollars for one project – the Maryland Transit Administration’s Purple Line.

It would run from Bethesda to New Carrollton and require not only federal dollars, but likely money from the private sector as well.

While money from the new transportation bill does help the Purple Line, it doesn’t guarantee anything. Federal dollars as well as private investors are still necessary, says Lt. Gov. Anthony Brown.

Brown, who is running for governor, says he’s confident both the Purple Line and Baltimore’s Red Line can be built with a mix of federal, state and private dollars. He has been actively lobbying companies to find a partner to help build the 16-mile light rail.

In Virginia, Transurban built the Beltway Express Lanes through a similar partnership.

The Purple Line could open by 2020.

WTOP’s Ari Ashe contributed to this report. Follow Ari and WTOP on Twitter.