Two of three companies in the running to design and build a new trolley line to Somerville certified they can do the work within the MBTA's threshold of $1.319 billion, allowing the roughly $2.2 billion project to move forward and letting T managers breathe a little easier.

"We were confident with the new design that it could be built for the amount of money that we had, but you don't know that until the industry comes in and tells you," Transportation Secretary Stephanie Pollack said at a meeting Monday. She said, "Now we know we have a project that we can build from the resources we have available, and while there's lots more work to be done, I think that today really marks the day when we can be sure there's going to be a Green Line Extension."

The design-build contract will be the largest contract for the project, which was nearly derailed by cost-overruns two years ago and underwent a switch in the company hired to oversee construction earlier this year.

John Dalton, program manager for the Green Line Extension, told reporters he was "relieved" when he learned Monday that two of the three firms competing for the contract certified they could do it within the budget. He did not specify which of the three construction firms was unable to certify that it met the T's cost requirements.

"We're going to hold off on being specific about that while we're still in the procurement process," Dalton told reporters after briefing the MBTA Fiscal and Management Control Board.

In February the T identified three groups qualified to handle the construction: GLX Constructors, Green Line Partners, and Walsh Barletta Granite, JV.

The actual prices and other aspects of the bids will be unveiled at a "public pricing opening" scheduled for Nov. 17, MBTA General Manager Luis Ramírez told the control board.

"We still have some very big steps in front of us," Dalton told the board.

The T control board and the Massachusetts Department of Transportation Board – responsible for funding the project – considered cashiering the trolley extension after transportation officials in 2015 disclosed that it might run as much as $1 billion over-budget. The T scrapped plans for the group White Skanska Kiewit to build the project, pared down plans for station amenities, and ultimately elected to proceed with a somewhat modified extension project.

"This is a project that could have easily been canceled," Control Board Chairman Joseph Aiello said Monday. He credited Gov. Charlie Baker with encouraging T officials to stick with it, quoting the governor as saying, "Get at it. Try to get it right."

The extension will allow trolley passengers to travel outbound from a new Lechmere Station in East Cambridge to six new stops in Somerville and Medford.

Last spring, the T chose CH2M Hill to be project and construction manager for $57 million but the agency later had to drop the company after it was acquired by one of the firms in the bidding for the actual construction, creating a conflict of interest. The T has worked out an arrangement with HAKS Engineering to take on the management role, according to T spokesman Joe Pesaturo.

Dalton said it is unlikely that sort of scenario would repeat itself.

"I have no reasons to think that will happen, or might happen. I think it very unlikely, but I can't completely tell you 100 percent that will not happen. That's completely speculative," Dalton told reporters.

Asked what would have happened if all three bidders were unable to certify they could meet the T's cost threshold, Dalton said officials would have then needed to "consider plan B."