Starting next spring and summer, the MBTA would eliminate commuter rail service on weekends and after 9 p.m. on weeknights, cease running all ferries, scrap 25 bus routes, including one that runs along Dorchester Avenue, halt subways and buses at midnight, and scale back more transit options under a package of service cuts officials unveiled on Monday.

The proposal, which will be the subject of a month-long public comment period ahead of a final vote in December, would shave more than $130 million from what the T spends on running buses, trains, and ferries.

While the T has faced financial pressures for years, it was pushed into an unprecedented crisis by evaporating ridership and fare revenue amid the COVID-19 pandemic. The slide in T revenues commenced in March, just as the House was passing new transportation revenues, a push that has so far drawn no response from the Senate.

The plan unveiled Monday puts clear contours on how MBTA and Department of Transportation officials plan to cope with a $579 million shortfall, and could reshape transit in eastern and central Massachusetts for years.

T officials aimed the steepest cuts at routes where ridership has declined the most during pandemic and in areas where commuters have access to alternatives, but the vast majority of the system — which hosted upwards of 1.2 million rides a day before Covid struck — will be affected in some way.

Layoffs are almost certain, though the timing and number are not clear. Fare hikes are not currently under consideration, as the T evaluates a future in which many of its former users may continue working from home.

“Using limited resources to operate nearly empty trains, ferries, and buses is not a responsible use of the funding provided by riders, communities, and taxpayers, and it does not help support the transportation needs of our region,” MBTA General Manager Steve Poftak wrote in an open letter to riders. “Saving resources now will help the MBTA to bring back service when it is needed after the pandemic has faded.”

Lawmakers, transportation justice activists, and organized labor leaders responded with quick and pointed criticism, many describing the potential slashes as “austerity” imposed by the Baker administration.

Opponents argued that the cuts would make commuting more difficult for riders who rely on public transit to get to essential jobs, a large portion of whom are low-income or people of color, despite the T’s best efforts to limit the brunt of the changes to routes where they will have the smallest impacts.

They also warned that making transit less accessible could push more workers onto roadways, exacerbating traffic that had been among the worst in the nation before the pandemic hit and stalling the state’s efforts to rein in greenhouse gas emissions.

“It is the same old song of MBTA officials pushing austerity, rather than daring to ask the wealthy to pay their fair share, despite the strong public support for new revenues that will ensure high quality, affordable, safe public transportation,” said Jim Evers, president of the Boston Carmen’s Union, which represents thousands of T employees, in a statement.

The union will push for a moratorium, he said, on any additional cuts that would affect essential workers in jobs critical to the state’s fight against the coronavirus.

Under the plan outlined on Monday, service levels would drop an average of about 15 percent on buses, 30 percent on subways, and 35 percent on commuter rail.

The changes are likely to remain in place for years, although MBTA officials said they will monitor trends and respond accordingly if they notice increasing demand or crowding.

T staff will host a series of public meetings over the next month, focusing both on specific regions with T service and on the system as a whole, to solicit feedback about the plans before the Fiscal and Management Control Board votes on the final package on Dec. 7.

The T also has published an interactive map on its website laying out the line-by-line and route-by-route cuts on the table.

All of the T’s core subway lines would run 20 percent less frequently under the proposal, saving tens of millions of dollars in operational costs. (T officials initially described off-peak changes as an “additional 20 percent,” but later clarified that there is no planned difference between peak and off-peak subway service changes.)

The Green Line’s E Branch would also stop running trolleys at the Brigham Circle stop in the Mission Hill neighborhood, replacing the final five stops with bus service for the fewer than 1,000 commuters who use them.

Both subway and bus service would stop at midnight, no longer running beyond that point until the start of service the next day, affecting more than 2,000 riders based on September figures.

The proposed changes to the bus network, which had the highest level of pre-pandemic ridership and serves a significant portion of commuters deemed “essential workers,” vary significantly by route. Essential bus routes would see an average reduction in frequency of about 5 percent, while non-essential routes would cut trips by an average of 20 percent.

The T would eliminate 25 of its 169 bus routes, 7 of which are within a quarter-mile of another route or subway, 6 of which have transit-critical riders but low ridership, and 12 of which have exhibited low demand and serve less dependent populations, officials said.

In Dorchester, the 18 bus line, which runs between Ashmont and Andrew stations on a route that mainly parallels the Red Line— would be discontinued.

Another 14 routes would be consolidated and 5 would be shortened. Officials also proposed eliminating the suburban subsidy program partly funding additional service in Bedford, Beverly, Burlington, Lexington, and Mission Hill, plus hiking fares on about 1 percent of trips using the RIDE paratransit service.

On the commuter rail network, T leaders will suggest cutting more than a third of pre-Covid service, largely by shutting the system down on weekends and after 9 p.m. on weekdays. The exception would be the Fairmount Line, which would be replaced by buses on the weekend and close up to an hour later than other lines during the week.

Weekday service at both the peak and midday would be trimmed, too, with the T cutting the number of trains per day from 505 to 430.
All MBTA ferries, including the Charlestown, Hingham, and Hull routes, would cease operations indefinitely if the plan is implemented.

Several capital projects could wind up paused indefinitely to redirect tens or hundreds of millions of dollars in funding, such as purchase of new commuter rail cars or improving signage across the system.

The T says it is now only transporting 330,000 trips on an average weekday, but is running the same levels of service it ran to serve 1.26 million daily trips prior to the pandemic.

T staff had previously said that the changes are likely to be permanent, but Pollack and Poftak clarified Monday that they are not seeking immutable cuts to the agency’s spending on service. They said they hope to use the changes as an opportunity to build back a more equitable system than existed before the pandemic.

Evers said the FMCB “would be failing riders and the public yet again” if the board approves cuts before President-elect Joe Biden takes office, hinting that he believes a Biden administration would authorize additional stimulus or infrastructure funding.

However, several officials said on Monday that they do not intend on reversing course even if a new batch of federal aid arrives, cautioning that it would be foolish to close next year’s budget gap with one-time funding only to face a new process of planning cuts the following year if fare revenue remains severely diminished.

The T has already exhausted about $827 million from the CARES Act to close gaps in fiscal years 2020 and 2021, and Poftak said he wants to wait until revenues are “durable” before officials begin to think about selecting which services to restore or which new options to embrace.

“Even if we were to get an infusion of money from a third party, it’s important not to just react and say, ‘Okay, let’s put the old schedules back together and let’s call it a day,’” Joseph Aiello, chair of the FMCB, said at Monday’s meeting. “There’s certainly going to be some elements of the system that are going to take much longer to recover than others, and I don’t think any of us are interested in not being efficient with the use of taxpayer money.”

Boston City Councillor and mayoral candidate Michelle Wu called the plans to cut service “short-sighted and dangerous.” The council unanimously opposed the cuts in a resolution last week.

“These cuts will impact the very essential workers – many from low-income communities and communities of color – who have been the heroes of this pandemic and who rely on the MBTA daily,” Wu said. “Longer waits, loss of weekend service, and eliminated stops means more risk to public health, more traffic, and more burden on the very communities devastated by the pandemic.”

Matt Murphy and Bill Forry contributed to this article.