It has been able to balance its budget through a hiring freeze and savings on travel and events. But, said David Greene, Colby’s president, “in the long run, that is not a winning strategy.”

Like other administrators, Mr. Greene is hoping to reopen with classes on campus, rather than online, even if it means deferring the start of the fall semester. “Our whole model of education and all of its power comes from close human interaction,” he said.

But he can only delay so long. “If we had to start in October instead of September, that is not a real problem for us,” he said. “If we had to start in November instead of September, that’s probably not a real problem. What if we started in January and went through August? That would be a very different kind of problem.”

Although Congress provided $14 billion for higher education in the $2 trillion rescue bill signed by President Trump last month, a large chunk of that, $6 billion, was in the form of emergency cash grants for students in financial distress.

The rest of the bailout amounts to just 1 percent of total university expenses. College presidents say that will not be enough to protect some institutions from slashing their staff and programs, cutting back scholarships or perhaps even going under. They are asking for at least $46.6 billion in aid, to be divided equally between institutions and students, in the next stimulus package.

There are some 4,000 two-year and four-year public and private colleges and universities in the United States, educating roughly 20 million students. They generated about $650 billion in revenues in 2016-17, and in some states, like California, Iowa and Maryland, they are the largest employers, according to the American Council on Education, a trade group.

The council predicted in an April 9 letter to House Speaker Nancy Pelosi that college enrollment for the next academic year would drop by 15 percent, including 25 percent for international students from countries like China who often pay full tuition, helping universities meet their budgets and afford financial aid for Americans.