For the past two months, inbroadcast interviews and theop-ed pages of The New York Times, Brown University President Christina Paxson has argued colleges must reopen in the fall or higher education will crumble, and dozens — if not hundreds — of colleges will go under.

Testifying before a virtual U.S. Senate committee last week, Paxson ticked off a series of steps needed to restart in-person classes and get back on track the country’s 20 million college students.

“Testing and more testing,” the economist and public health expert said. “Tracing, social distancing, masks and hygiene measures. We’re changing how we use lecture and classroom spaces. We’re adjusting living arrangements and dorms. This work is complex. It is all-consuming. It’s very expensive.”

Whatever the cost, Paxson said, it’s worth it, because so many students say they’d delay getting their degrees if they couldn’t return to campus. “That would be bad for them and bad for the country,” she said.

Reopening colleges is not as simple as turning a key. College presidents, faculty, students and their families are all weighing the costs and benefits of returning to face-to-face instruction in the fall, and administrators are also assessing the challenges of testing, tracing and quarantining. Most colleges are not expected to make their final decisions about the fall semester until early next month.

In Massachusetts and across the country, colleges areasking the government for testing help and protection from potential lawsuits. Some Massachusetts state universities, including UMass Amherst, arelooking at housing students in single dorm rooms and shifting the calendar so classes start weeks early and students return home before Thanksgiving. Others are evenexploring using apps to track where students congregate in order to monitor the spread of the virus.

At stake are public health, civil liberties and the economy, so there’s a lot of pressure on college presidents to get this right.

“They have lives in their hands, and also they have the future of their college in their hands,” said economist Robert Kelchen, who teaches higher education finance at Seton Hall University in New Jersey.

Kelchen predicts colleges will only open their most essential classes, like COVID-related research labs and nursing programs. “And they’ll try to get some students living on campus if they’re driven by residence hall revenue,” he said.

While there’s some buzz about digitally tracking students and staff on campus, Kelchen said that would raise questions about civil liberties and the limits of technology.

“Will people be willing to turn on the apps?" he asked. "And then also inside many college classrooms, frankly, cell phone service isn’t that good. So can you tell where people are congregating in every case?”

Since most colleges’ reopening plans hinge on getting legal protections, thousands of tests and millions of dollars in state and federal aid, poorer institutions may be left to scrounge not for apps, but for masks and disinfectant wipes.

A survey conducted in May by the American Council on Education, an umbrella group of colleges in Washington, found the majority of college presidents say reopening in the fall is very or at least somewhat likely. But presidents of cash-strapped community colleges were less likely than presidents at four-year public and private colleges to say they “very likely” would resume in-person classes this fall. Kelchen said that’s because community college leaders tend to be more realistic about their risk.

“When most students live off-campus and commute, it’s hard to control students on campus,” he said. “It’s also hard to space classes out when there are already classes running on nights and weekends, and they don’t have the resources to buy the miles of plexiglass and gallons of hand sanitizer that they need.”

Circumstances are changing so fast — week-to-week, day-to-day — that few colleges know what they’ll do next exactly. Still, nearly every day, another college announces its intention to go in-person or stay online, or offer a mix of both.

Last week, six graduate programs at Harvard — the divinity, education, design, public health, government and law schools — announced they’ll keep classes online for the entire fall semester.

“I’ve got a lot of adapting to do this summer and yet I get to stay in sweatpants, so, you know, there’s pluses to everything,” joked former homeland officer Juliette Kayyem, who teaches at Harvard’s Kennedy School of Government and is a WGBH News contributor.

Kayyem said the Kennedy School’s decision to stay online was widely expected.

“I think the general tone was that this was more likely than not,” she said. “Now it’s just sort of ensuring that there’s a sufficient student pool to teach and that we as a faculty are flexible enough to make online teaching creative and interesting enough.”

There’s still no word on whether Harvard’s undergraduate college will stay online or resume residential education in some way. Kayyem said Harvard’s silence on undergraduate education is telling.

“At its core, despite the fact that it’s a major university, it is ultimately a college for students, and as you see other colleges begin to test new systems of calendaring, there’s still a question about whether Harvard may try to not draw such lines for its undergraduates,” she said.

“Anything anybody tells you today has to have a big qualifier of ‘depending on what happens between now and the end of August,’” said Frederic Lawrence, CEO of the Phi Beta Kappa Society. As a former dean and president at George Washington University and Brandeis University, over the years, Lawrence has spoken with thousands of alumni of different schools.

“When I meet a new person, one of the icebreakers I always do is, ‘Just tell me a memory from your time at the school,’” he explained. “You know something? Those never take place in a lecture hall. Not a single time. They take place walking on campus. They take place in a faculty member's office. They take place in a dormitory, one of those late-night discussions that changes your life. So those things are being compromised now.”

During the Senate hearing on how college students can safely return this fall, Sen. Elizabeth Warren pressed Paxson about the potential human costs, asking her why Brown and other colleges, which are already facinglawsuits seeking tuition refunds for the spring semester, are now requesting new protections against being sued if a low-wage staff member, elderly professor or young student becomes sick.

“Would it make you more comfortable or less comfortable as the parent of an incoming student?” Warren asked.

“I do not want protection from being careless,” Paxson responded. “The fact is, though, many institutions are very nervous that even if they play by the rules scrupulously, that they will still be subject to class-action lawsuits.”

For now, without a vaccine, all roads back to campus this fall lead through widespread testing, tracing and social distancing.