The MBTA has notified several firms working on the over-budget Green Line Extension project that it is acting to end their current contracts, and the agency plans to install a new project manager as part of a restructuring of the project management team.

The move comes after the MassDOT Board and the MBTA Fiscal and Management Control Board met publicly and privately on Wednesday to consider options to salvage the project, the cost for which has ballooned by about 50 percent, or $1 billion, higher than budgeted.

"Today’s actions are necessary steps to resolving the future of the GLX project," FMCB Chairman Joseph Aiello said in a statement.

T General Manager Frank DePaola told general contractor White-Skanska-Kiewit, project and construction manager HDR/Gilbane, independent cost estimator Stanton Constructability Services and final designer AECOM/HNTB the agency would be taking steps to end their current contracts.

Construction work already underway will continue, according to the MBTA, but no new construction work will be awarded during what the MBTA is calling "the start of a transitional period."

MBTA and MassDOT officials listened Wednesday to options of how to proceed with the extension from Lechmere in Cambridge through Somerville and into Medford. Though Transportation Secretary Stephanie Pollack said she would not take cancelling the project off the table, officials are considering scaling back the scope of the project or pursuing different types of competitively bid design-build contracts for the work.

According to the statement issued Thursday, the Fiscal and Management Control Board believes the MBTA must reduce the cost of remainder of the project "by adjusting its design," accurately determining a budget, determining the "best means to procure and deliver the design and construction, and by ensuring "sufficient funding by engaging multiple funding sources."