The completion date of the Green Line extension will likely be pushed back yet again as MBTA officials look for ways to drive down the costs and find new revenue to pay for the project.
Officials do not yet have an estimate for when the extension could be complete, but top state transportation officials acknowledged that the project is unlikely to meet its latest timeline, which pegged some of the stations opening by 2017.
On Wednesday, Transportation Secretary Stephanie Pollack told the state transportation board that the next major phase of the project might not move forward until next spring, at the earliest. Construction on that phase was slated to begin this fall.
State officials, who say stopping the project is still on the table, will present their recommendations for the project at a Dec. 9 meeting.
"We don't want to put additional Commonwealth dollars at risk until we've moved forward on the project," Pollack said.
The project was threatened earlier this year when officials revealed the long-awaited extension — which will bring the Green Line to Medford and Somerville — could cost about $1 billion more than expected.
Pollack told board members Wednesday that the MBTA has hired four firms to help officials look into how the costs ballooned, whether officials should replace the construction firm chosen for the project, and whether the state will need to pitch in additional bond money.
Asked about the delays, Frank DePaola, the general manager of the MBTA, said, "At this point, we want to deliver a project."