Local legislators said Tuesday that it is time to reconsider a proposed $1 billion commuter rail line to New Bedford with the Massachusetts Bay Transportation Authority bending under $8 billion in debt.

The lawmakers said the state is having trouble affording the services and infrastructure it already has without expanding into new areas.

"We have to have some frank discussion about whether we can afford this," state Sen. James Timilty, D-Walpole, said of the proposed train to New Bedford and Fall River.

South Coast communities have been pleading with the state for years to extend the MBTA's commuter rail service from Boston.

Gov. Deval Patrick has committed to the project and promised he will not let the South Coast down, as previous governors have. However, the MBTA said it has serious financial problems because its income from the state sales tax is down due the slumping economy and it has staggering debt service payments from its $8 billion in borrowing.

General Manager Daniel Grabauskus said the MBTA will either have to raise fares by a "hefty" amount by 2010, or the Legislature will have to find more funding for the agency.

Timilty opposes sending New Bedford-bound trains through Attleboro and Norton but also said taking on another $1 billion in debt at this time does not make sense.

Especially, he said, because he considers the $1 billion estimate on the low side for the South Coast project.

State Rep. Steve D'Amico, D-Seekonk, said the Patrick administration is looking for creative financing methods for the South Coast rail, such as tapping into the development potential of land around the new line.

"But it's too early to tell," he said.

D'Amico's district includes parts of Swansea so he said he knows how badly South Coast communities want the rail service.

State Rep. Richard Ross, R-Wrentham, said he agrees with Timilty about the cost of the project.

"When you are having tough times, it is not time to look for new services," he said.

Ross also said the MBTA and other state agencies should start cutting their own expenses, rather than ask taxpayers for more money. "I'd encourage them to run it more efficiently," he said of the MBTA.

Joe Pesaturo, a spokesman for the MBTA, said the authority has tried to lower costs by reducing overtime and wages.

However, he said revenue is not keeping up with increases in other costs, such as fuel.

Ridership is up 6.1 percent over the past year, but energy costs are up 25 percent, he said.

The biggest financial problem, he said, is the $8.1 billion in debt the MBTA has.

Timilty said the state's past problems are now coming to surface and this Legislature will continue to deal with them.

For instance, he said the Legislature is putting regional transit authorities under a stricter budget process.