BOSTON (AP) – Skepticism is growing to a proposal by Gov. Deval Patrick to build an estimated $1.4 billion commuter rail from Boston to Fall River and New Bedford, with critics saying the administration has yet to come up with a viable plan to pay for the project.

Patrick earlier this month named a project manager and embarked on a $2 million study of the long-delayed rail plan, including looking at how much new development could be sparked along the rail corridor – and whether that new development could help pay for the project.

Not everyone is convinced.

Critics say that, coming off the nearly $14.8 billion Big Dig and faced with a crumbling transportation infrastructure, the last thing the state can afford is a pricey new commuter rail line.

And at the Statehouse, some lawmakers are pushing for a moratorium on all future MBTA rail expansions, including the New Bedford project.

“Rather than promising the people of New Bedford and Fall River that we are going to be spending a billion-four, the priority of the administration should be making sure the bridges and roads we have right now are drivable and useable,” said Senate Republican Leader Richard Tisei, R-Wakefield.

Tisei is pushing for the moratorium. He points to a recent report that found Massachusetts will need to come up with $15 to $19 billion in new revenues over the next two decades just to maintain the state’s existing roads, bridges and transportation infrastructure.

“At this point when it comes to transportation, we all need to take a deep breath,” he said.

Michael Widmer, president of the business-backed Massachusetts Taxpayers Foundation, sits on the transportation panel that came up with the report. The panel is currently working on a second part of the report, which could include recommendations for coming up with the needed revenue, such as a hike in the gas tax.

Widmer said the notion that additional tax revenues from new developments along the commuter rail route could pay for the project is a stretch.

“I don’t know of any example of a project this big either in Massachusetts or anywhere else that would be funded by new development,” he said. “You could carve out a district, but you’d be capturing existing revenues.”

Patrick is moving ahead with the initial planning stages.

The target of the $2 million, 18-month report is to look at potential long term benefits of the new commuter rail through economic development and land use that takes advantage of the potential for the creation of new jobs and new housing along the route.

In announcing the study and new project director earlier this month, Patrick’s Housing and Economic Development Secretary Dan O’Connell said the state can build new public transportation systems alongside sustainable development.

“Our goal here will be to maximize the leverage of new private activity, and the tax revenue that activity will bring to the commonwealth,” he said.

Steve Smith, executive director of the Southeastern Regional Planning and Economic Development District, is also upbeat, although he concedes there are still fiscal challenges for the project.

“The argument that we can’t afford it, I can understand that, but in some ways it rings a little hollow because they’ve afforded it everywhere else in eastern Massachusetts and Rhode Island,” he said pointing to other MBTA commuter rail lines. “There is a question of equity.”

He also said that steadily increasing traffic on Route 24 may end up forcing the issue. Since 1984, traffic has tripled, he said, and shows few signs of slowing.

He said one possible answer to the money question – one that he acknowledged could be politically difficult – is an idea he said has been pushed by state Rep. Antonio F. D. Cabral, D-New Bedford.

The proposal would create a mass transit fund through a new sliding “greenhouse gas fee” on cars, trucks and motorcycles, based on fuel efficiency. Depending on how much the fee is, the plan could raise up to $170 million a year, Smith said.

That could run into trouble at the Statehouse, where lawmakers and Gov. Deval Patrick have shied away from talk of anything that smacks of a new tax.

AP-ES-05-27-07 1452EDT