ANNAPOLIS -- Members of a Senate panel voiced concern Tuesday that money funded by a proposed increase in the state gasoline tax would go toward mass transit instead of roads.

Members of the Senate Budget and Taxation Committee questioned whether the projected $4.3 billion that would be raised by 2019, mainly though a wholesale tax on gasoline, would go toward aging infrastructure or mostly mass transit, such as the proposed Purple and Red light rail lines in the Washington suburbs and Baltimore, respectively. The legislation doesn't specify how the funds must be used.

"The fact is, [mass transit] is where the money is going to go," said Sen. David Brinkley, R-Frederick and Carroll counties. Part of the increased transportation revenue would be used to help ensure the federal government provided $900 million in matching grants, but Brinkley said there was no guarantee the federal government would come through with the cash.

About 9 percent of Maryland workers age 16 and up use mass transit to commute to work, according to the Census Bureau.

The measure would apply a 1 percent wholesale tax on gasoline starting July 1, meaning an increase of about 4 cents per gallon at the pump. The bill would ratchet that tax up to 3 percent by July 1, 2015. If Congress fails to pass a bill requiring online retailers to collect state sales taxes, the wholesale gas tax would jump to 5 percent by July 1, 2016, leading to a total increase of about 19 cents per gallon over today's prices.

The measure also would index Maryland's flat 23.5-cents-per-gallon gas tax to inflation but caps any increases at 8 percent to protect against years with wild inflation.

Gov. Martin O'Malley's chief of staff, Matt Gallagher, argued that the money was badly needed for aging infrastructure as well as new projects.

Gallagher pointed out that 41 percent of Maryland roads are in poor or mediocre condition and 55 percent of urban highways are congested.