“New York’s subways, trains, and buses are our very lifeblood,” said Senator Chuck Schumer, a Democrat from New York and the Senate minority leader. “Senate Democrats are leading the charge to include substantial support for the whole system in any package Congress will next consider to keep our vital public institutions stable and operating.”

State and city officials have said they are not planning to reduce service on the region’s vast transit system, which typically serves around eight million passengers every weekday. They have emphasized that it is important to keep the system operating so health care workers can get to work.

But the M.T.A. is particularly vulnerable to the sudden and precipitous economic downturn since it relies on a mix of funding from federal, state and city government — all of which are grappling with their own challenges — to operate and maintain its system.

“They are a barometer of the regional economy, a much more immediate barometer for things to come,” said Nicole Gelinas, a senior fellow at the Manhattan Institute, a conservative research group.

Revenues from fares and tolls, which contribute around half of the M.T.A.’s operating budget, and dedicated taxes, which provide another third of that budget, are already taking a hit as ridership falls and the pandemic sets off sweeping layoffs and business failures across the city.

Officials have urged those who can to avoid subways and buses and enacted sweeping regulations, like closing schools, Broadway theaters, museums, movie houses, bars and allowing restaurants to remain open only for take out and deliveries, that have all but shut down New York.

The draconian measures are meant to curb the spread of the virus in New York City, where the number of confirmed cases climbed to over 1,000 on Tuesday.