With Chicago-area gas prices pushing the $4 mark and pending federal legislation that would slash millions of dollars in funding for local public transit, a group of city transportation advocates is calling for more funding and improved services.

Riders for Better Transit and the Active Transportation Alliance held a press conference Wednesday morning at Pritzker Park near the Jackson Red Line station at Van Buren and State Streets. The group is throwing its support behind the Transit Fast Forward Bill, which would add a tax of two-fifths of a cent per gallon of gas to the six Illinois counties served by the CTA, Metra, and Pace systems.

In a press release the group said the money raised by the tax will help reduce future fare increases and provide funding to rebuild Chicago’s aging public transit infrastructure.

Advocates like Ron Burke, executive director of the Active Transportation Alliance, said the added tax, which would increase the average family’s spending on gas by about $4 a year, would generate about $11.6 million for transit in 2013.

“The math is clear. If we don’t create additional funding for transit, we’re almost certainly going to see more service cuts, more fare increases. We need to address this situation soon,” Burke said at today’s press conference.

Stephen Schlickman, executive director of the Urban Transportation Center at UIC, also spoke at the conference. He said the tax could lessen the amount of congestion on the city’s highways by encouraging more people to use public transportation.

“We need an expanded transit system so that people who feel like they can only drive will have those options,” Schlickman said.

Burke said he and other members of his group have been meeting with state legislators in Springfield over the past few days to round up support for the bill, but he admitted that any tax increase will be an uphill battle, especially in an election year.

Ron Baiman, director of budget and policy analysis at the Chicago-based Center for Tax and Budget Accountability, agreed that the legislation will face a steep challenge, but said the tax would be smart fiscal policy for the city.

“Supporting public transportation by adding a little cost to the private sector, a tiny increase in cost for most drivers, would be a good thing,” Baiman said in a phone interview Wednesday afternoon. “Public transportation has all kinds of benefits. It contributes to economic development by getting people to shops more easily. It makes for more efficient consumers, especially for lower income people.”

Baiman also pointed out the environmental benefits of public transportation, which helps reduce the amount of cars on the road and keeps urban sprawl in check by creating more centralized residential areas.

Currently the bill has only one supporter in the state legislature. Senator Martin Sandoval (D-Chicago), who is also the chair of the Senate Transportation Committee, introduced the bill on February 1. Sandoval did not return a phone call by posting time.