The MBTA's oversight board will be asked to vote Monday on a set of service cuts that would take effect this winter and spring, while other major decisions about the transit system will be delayed for several months amid an uncertain outlook.

T officials will present a plan for approval that would suspend 20 bus routes, eliminate weekend commuter rail service on seven out of 12 lines, close five commuter rail stations, trim the frequency of train and bus trips, reduce Hingham and Hull ferry schedules and more.

The changes would roll into effect in January and in March in an attempt to take advantage of significantly lower ridership in this stage of the public health crisis -- when the T is, on average, transporting less than a third of pre-pandemic riders -- to save money as the agency stares down a massive budget deficit inflicted by shrinking fare revenues.

Decisions about service in fiscal year 2022, which starts in July 2021, will be pushed off until the agency's budget deliberations in February and March. At that point, higher-ups could return to the Fiscal and Management Control Board with a proposal for additional cuts, or they could suggest reversing some of the existing changes and bumping service back up.

The cuts are on the table despite strong pushback from an array of interests, including members of Congress, and updated tax collection projections that point to a sizeable windfall for the transit agency.

MBTA General Manager Steve Poftak said the "bifurcated" decision-making will allow officials to get a better sense of ridership trends, the COVID vaccination timeline, changes in commuting behaviors and possible federal aid, all of which impact the T's financial outlook.

"I don't know that they're going to resolve themselves definitively, but we will have a lot more information in February and March than we do right now," Poftak told reporters during a briefing ahead of the FMCB's meeting.

Layoffs are still on the table, but Poftak did not offer any specific estimates on workforce impacts, saying officials are in "productive discussions" with labor leaders.

Although the proposal still calls for cutting some routes entirely, it has been scaled back from an earlier version in several areas to recommend reducing service rather than outright eliminating it, based on months of public opposition and feedback.

The latest plan no longer recommends halting bus and subway service after midnight, cutting the Hingham and Hull ferries, or replacing the final five subway stops on the Green Line's E Branch with shuttle buses. It would also trim frequency on the Blue Line -- which has seen relatively high ridership -- by a maximum of only 5 percent compared to 20 percent cuts on the Red, Orange and Green Lines.

Weekend service would remain available, albeit reduced from pre-pandemic levels, on the Worcester, Providence, Newburyport/Rockport, Middleboro and Fairmount Lines. Those five routes represent about two-thirds of COVID-era weekend ridership on the commuter rail, officials said.

At the moment, MBTA officials are not sure how much money the agency will save under the updated plan. The board could opt to change the outline before adopting it Monday, and officials said they would develop a new estimate based on the final version.

Poftak clarified during the briefing, though, that he expects the spending reduction to be less than the original plan proposed in November, which would have carried a net savings -- once accounting for the decline in ridership caused by less service -- of up to $95 million.

Like transit agencies around the country, the MBTA faces a major shortfall because fare revenue has evaporated during the pandemic. Previous estimates forecast a deficit of more than $580 million in fiscal year 2022.

Service cuts are just one component of a larger plan to grapple with that shortfall, alongside reallocating federal funding and trimming capital spending.

During Monday's briefing, Transportation Secretary Stephanie Pollack said the MBTA now expects a boost of $52 million in fiscal 2021 based on an improved sales tax outlook compared to earlier projections.

She contrasted the approach at the T -- whose latest plan would retain 85 to 90 percent of pre-COVID service hours for buses, 75 to 80 percent for subways and 70 percent for commuter rail -- with other American transit agencies.

"I do not see what the T is proposing as anywhere close to a doomsday scenario," Pollack said. "This is a service adjustment, which is providing more than adequate service for the number of riders we have and expect to have for the remainder of the current fiscal year."