U.S. hospitals are warning that they are so strapped for cash that, without some financial relief, they will be unable to meet their payrolls in a matter of weeks and some could be forced to close just as coronavirus cases are surging.

The American Hospital Association and three hospital chief executives spanning the country said in a conference call Saturday that a federal directive this week urging the cancellation of elective procedures — to conserve scarce resources for coronavirus patients — is halting the type of services that produce the most revenue.

And their ability to buy critically needed supplies — from protective gear to more hospital beds — is being stymied by the fact that private vendors are requiring hospitals to pay cash upon delivery, which they say they lack the money to do.

This stark portrait of the ground-level reality for hospitals, in communities where the pandemic has penetrated and those where it has not yet seriously struck, comes as hospitals and other cornerstones of the U.S. health-care system are pleading with Congress to provide large-scale financial relief.

The American Hospital Association, the American Medical Association and the American Nurses Association are urging Congress to provide hospitals and health systems $100 billion in emergency aid. The Federation of American Hospitals, the trade group for for-profit hospitals, issued a call Friday night for at least $225 billion in aid.

On Saturday’s conference call, J. Scott Graham — the chief executive of Three Rivers Hospital in rural Washington state, where the pandemic has not yet surged — said the cancellation of elective procedures means “there are no patients coming. . . . As a result, all of the revenue that typically comes in to cover the cost of operating has dried up.”

Graham said that the hospital projects it will be able to meet its payroll for the next three or four weeks. But he said it has stopped paying its vendors and has been urging its local bank to extend its credit limit — unsuccessfully so far.

“If we don’t get some assistance in the next two weeks, we will have to start having conversations with doctors and nurses and our community” about the need to close, he said. “We are concerned we will not be able to be around, because of the financial hit we are taking, by the time the surge hits us.”

A hospital executive in a very different environment, LaRay Brown of One Brooklyn Health System, which serves mainly low-income patients in the New York City borough, said, “We have less than two weeks cash on hand.”

That system of three hospitals, nursing homes and community health centers anticipates extra costs of more than $30 million per month, she said. It is racing to set up tents for testing and screening, has hired additional staff as others are isolated or home caring for children, and needs somehow to fulfill a new order by New York Gov. Andrew M. Cuomo (D) to increase hospital bed capacity by 50 percent.

“We literally need to buy the beds,” Brown said. But with vendors insisting on being paid at the time they are delivered, she said, “we can’t buy the equipment . . . if we don’t have the immediate cash.”