U.S. Rep. Michael Capuano has been a staunch, and patient, champion of the Green Line Extension project for decades. He wasn't happy when he learned of the budget deficit, but no one would say he should have been surprised.

"My thoughts were very simple, it was like, 'Oh, God. Here we go again. It never stops,'" Capuano told WGBH News Tuesday.

Capuano was pivotal in landing around $1 billion in federal funds for the project last year that made the dream, for the first time in years, seem like it could be a reality for Somerville and Medford residents.

Capuano said he's going to look forward for ways to get the extension stabilized, and doesn't know where the blame lays for the massive budget shortfall. Anyone who's represented the City of Somerville and then a congressional district for almost 40 years has to approach transportation in the Commonwealth with an arsenal of grains of salt.

"Can anybody be surprised when a major transportation project in Massachusetts is found to be significantly undervalued?" Capuano said.

Somerville Mayor Joe Curtatone is looking toward the future and how to continue construction in his city. The budget shortfall, he said, is a reason to look at new creative financing methods and to find ways to cut back on costs.

"We're working with the governor and his team to solve the problem — a lot of smart people in the room," Curtatone said. "The goal is to keep the Green Line going, which is under construction today, and put forth a project in a predictable fashion that turns that number down."

'Can anybody be surprised when a major transportation project in Massachusetts is found to be significantly undervalued?'

The Massachusetts Department of Transportation revealed Monday that the project's budget could suffer from as much as $1.08 billion in cost overruns, leaving Massachusetts with an unrealistic price tag to pay. The reasons for the budget blowup range from a spike in construction costs to old-fashioned bad budget assumptions when the project was on the drawing board.

It's now estimated by state officials that the entire project will be well over the original $1.992 billion cost and assume it will end up somewhere between $2.7 and $3 billion to finish the extension.

"While we're surprised at the high increase or spike in the costs, as we examine what is happening around the country, we're seeing the direct costs on these major infrastructure projects are rising exponentially," Curtatone said.

Capuano has been worried for some time that a governor could act to cancel the project, as Baker has the opportunity to do now. In a letter to then-Transportation Secretary Richard Davey in 2011, Capuano wrote that "The most important thing we can do is get this project as far down the road as possible while Governor Patrick, an honorable man and great supporter of [the Green Line extension], is in office. After generations of mistreatment, the people of Somerville deserve more than unenforceable promises that can be ignored by later, less noble administrations."

Capuano doesn't think Baker is that less noble administrator, but what the congressman wants out of Baker now, he said, is a timeline for how to rectify the situation moving forward. Capuano said he's reasonably confident that Baker does want to get the extension project done and won't cancel it.

"He won't do that," Capuano said. "I've had these discussions with him, he's not at that point."

"I would be a serious opponent to cancelling the project, and I've told the governor that," Capuano added.

Capuano was, even as far back as 2012, openly taking bets that the Green Line Extension would not begin on schedule.

At a celebratory groundbreaking for the very first stages of pre-construction on the extension at a Union Square brownfield in Aug. 2012, Capuano told the State House News Service that the Patrick administration had promised far more on transportation than they could possibly pull off in the final years of Patrick's second term.

"What I want from the [Patrick] administration is, I want honesty and truthfulness in spending," Capuano said at the time. "I've just suggested to any number of people, I'm willing to take a bet right now that there will not be a Green Line station [in Union Square] in 2017."

And do not expect the feds to pony up any more funds to get those trolleys to Medford.

"The federal government will not be coming in with additional money to save this project," Capuano said. "They told them that from day one. If they need more money, the problem is they will then go to the back of the line which will delay this project way too long."

Baker and his team are now the ones who need to figure out how to make the extension possible within the limited funds available.

"[The Baker administration] are the ones who are mainly going to have to get back together with much sharper pencils and try to make this project work," Capuano said.

Capuano said he is open to whatever realistic steps need to be taken to get the project completed, one way or another.

"Does it mean we go from seven stops to six stops? I don't know," he said, adding that the project's already been delayed about 20 years and that another three-to-five-year delay is one of several legitimate approaches to handling financial problems.

The former mayor of Somerville says he wants "service to the current people of Somerville, who have been underserved and overcharged forever."

Capuano described Baker's handling of transportation as "so far, so good," and is sympathetic to the challenges he inherited — some from his predecessor and some from Mother Nature.

"Like anything else, you inherit a system, in this case a project, and in this case in particular, they inherited a winter that was monstrous," Capuano said, adding that it will take about a year to determine whether Baker's been successful in turning around transit in the state.