WITH A $300 million to $600 million budget shortfall expected next year, MBTA officials on Monday began zeroing in on service cuts that would save as much as $255 million and started exploring ways to use capital funds to cover operating expenses.

In a presentation to the Fiscal and Management Control Board, T officials indicated the service cuts are likely to fall most heavily on ferry routes, commuter rail lines, and some bus routes. Service on the ferry to Hingham and Hull and most commuter rail lines could be scaled back starting next spring. Bus service changes could begin in July 2021. The presentation also warned that many of the cuts could take years to add back and some would be permanent.

The officials said their goal is to preserve service on routes that serve low-income, minority riders with one or no cars. These riders in general have continued using the T during the pandemic and are more likely to return sooner.  Bus ridership, for example, is at 46 percent of pre-COVID levels while ridership on ferries is 11 percent, 12 percent on commuter rail, and 24 percent on subways.

T officials said they plan to present several detailed service reduction plans to the board on November 2, and implementation will begin next year. The officials said they will offer three major service reduction plans to produce savings of $60 million, $150 million, and $255 million.

Subway service is considered essential, T officials said, and only minor cuts would be made, including less frequent stops at stations or ending service at midnight.

Service on the Fairmount commuter rail line would be maintained, as would service on at least part of the Middleborough/Lakeville line (serving the Brockton area), the Newbury/Rockport line (serving Chelsea, Lynn, and Salem), and the Providence/Stoughton line.

Service on all the other lines could be scaled back. Options include eliminating weekend service, ending weekday service at 9 p.m., reducing or eliminating midday frequency, reducing the frequency of trains at peak periods, or closing stations.

The presentation said 65 percent of the T’s bus service would not change, but the remaining 35 percent could be pared back.

“Once implemented, it could take months to years to re-add service depending on mode, scale of reductions, actions taken, and financial certainty,” the presentation said. “Changes will be permanent and we will build back a network that better serves the region.”

Joe Aiello, the chairman of the control board, said the definition of permanent service cuts may mean different things to different people. He said his understanding is that any service being cut reflects problems with the T’s service delivery network pre-COVID.

Several transportation advocates who testified at Monday’s meeting urged the T to ask the Legislature for more money rather than start cutting services. Staci Rubin of the Conservation Law Foundation said the T was in crisis before COVID-19 hit and is now moving to catastrophe with the “horrific options” it is considering to cut service.

“We should not pit riders of the Newburyport/Rockport Line against riders of the Greenbush Line,” she said.

Members of the control board did not advocate for more state funding on Monday. Instead, T officials began exploring a policy that for years has been considered taboo – using capital funds to bail out the operating budget. The T took that approach for years decades ago, a practice that eventually plunged the transit system into a state of disrepair. In recent years, the T has stepped up its capital spending, but now T officials are talking again about using capital funds to cover operating expenses for a short period of time.

The Baker administration has asked the Legislature for its approval to use $60 million in capital funding to pay the salaries of employees working on capital projects. The Legislature previously barred the T from doing that because of past abuses.

T officials on Monday said they are also considering tapping as much as $460 million in federal funds over the next four years that normally would go for capital projects and using that money for preventative maintenance work normally covered under the operating budget. The shift is allowed under federal guidelines.

T officials also said they are beginning to review planned capital projects for ways to delay spending or cut it completely on expansion project.s that have not been started yet. They offered few details on Monday.

Aiello, the chair of the control board, said he was concerned about the high level of borrowing by the MBTA for capital projects, which shows up on the transit authority’s operating budget as debt service.

“This is shooting up at a rate that is worrisome,” he said, inviting officials from the Massachusetts Taxpayers Foundation to come to a meeting over the next couple months to discuss their concerns about the need to rein in capital spending.