WASHINGTON — Members of Congress on Monday ratcheted up pressure on American universities to make college more affordable, suggesting in the strongest terms yet that wealthy schools like Yale may be mandated by the federal government to spend a larger fraction of their endowments each year.

At a meeting with leaders across American higher education, Senator Chuck Grassley of Iowa put it simply: If schools do not take action, Congress will do it for them.

“It looks like they take the approach that they’re a storehouse for money, and they obviously should not be,” Grassley said afterward in an interview with the News. “Money serves a purpose, and the purpose of a university is the education of kids, so we ought to get the resources where the kids are.”

His remarks capped a day-long roundtable discussion with two dozen officials from across higher education on the subject of how universities spend their endowments, which the Republican senator has criticized — to much public notice — over the past year. Yale, though, has managed to get on Grassley’s good side after announcing in January that it would install a minimum endowment payout of 4.5 percent annually, which would result in a half-billion dollars in extra endowment spending over the next half decade.

In a hearing room here on Capitol Hill, where several university presidents spent hours bewailing a suggested mandatory spending rate, Grassley and Representative Peter Welch, Democrat of Vermont, warned that American colleges must stop keeping billions in the bank as student loans pile up and tuition increases.

Speaking to the assembled academics, Grassley, the ranking member of the Senate Finance Committee, said it would “make everybody’s job a lot easier” if universities committed themselves to reforming their endowment policies, rather than putting members of Congress in a position where they feel they must step in. In the interview, he reaffirmed that point.

“It’s kind of a situation where self-correction is really better,” he said. “They need to continue to do all they can to help families of need and they need to think in terms of money that comes in, give it out the door for an educational purpose.”

Monday’s roundtable came one year after the Finance Committee held a hearing on the matter, at which point Grassley began to muse about introducing legislation requiring at least the wealthiest of America’s universities to spend at least 5 percent of their endowments annually, as foundations are required to do.

College administrators scoffed at the idea, warning that it could leave universities dangerously vulnerable to the volatility of the investment market.

“We are not foundations that can reduce grant-making,” said Anthony Marx ’81, the president of Amherst College. “We cannot — will not — close the English Department or the Biology Department during a downturn.”

Princeton University President Shirley Tilghman, who was perhaps the most impassioned critic on Monday of Grassley’s suggestion, offered the same argument. “Endowments are not savings accounts. They are not rainy day funds, they are not piggybanks,” she said. “The income that is earned through investments is the working capital that we use every day to support our programs.”

And it’s not as if universities are just saving their money because they want to add to their gilded coffers, she said.

“Whenever we’re thinking about universities, particularly research universities, they are growing institutions,” she said. “When Princeton made its commitment to create its genomics institute, we did not turn around and cancel the Department of Classics. In fact, the genomics institute became an additional cost.”

Officials from across academia on Monday echoed a number of concerns that University President Richard Levin and other Yale administrators have raised about Grassley’s proposal in the last year. Levin has said the decision on setting an endowment payout should be a matter “of private regulation rather than public regulation.”

“What that effectively does … is to say, ‘We don’t care what the circumstances are [at each school],’ ” said Thomas K. Hyatt, a Washington attorney who specializes in working with tax-exempt institutions. “It takes that decision-making squarely out of the hands of the people who have a fiduciary duty to make those kinds of decisions — the board of trustees of those colleges and universities.”

Levin himself was not asked to participate in Monday’s discussion, said Richard J. Jacob, Yale’s associate vice president for federal relations. But Yale officials continue to monitor the situation; Jacob said he and another aide in the General Counsel’s Office watched the roundtable via webcast.

Plus, the University seems to already be on board with Grassley’s mission. Just a week after the January announcement about increasing endowment spending, Yale went on to specify that some of that spending would go toward paying for a sweeping new financial aid initiative, by far the most generous in the University’s history.

Levin said at the time those policy changes came at least in part because of Grassley’s concerns, and the senator on Monday repeated his praise for universities that have bowed to his pressure and taken action to increase their endowment spending or financial aid offerings in the last year.

It was all part of an effort to “embarrass” schools into shaping up, Grassley said. And it has worked; never before in his seven years as the senior Republican on the Finance Committee has the senator “gotten as much bang for my buck,” as he put it in the interview, on a single issue.

“Our hearing a year ago led them for the first time to think in terms of how much they’re allocating, and should they be embarrassed because they weren’t allocating enough,” Grassley said. “Obviously they were embarrassed because a lot of schools took a lot of action.”

Welch, who moderated most of the roundtable, made it clear he was not happy either. He criticized college leaders for being too closed-minded to the suggestion of a mandatory payout.

“The defensive reaction gave some suggestion … that there was some resistance from the education establishment about addressing what I think is an undeniable crisis in the escalating cost of higher education,” he said.

In the interview, Grassley he is not committed to introducing legislation to mandate minimum endowment spending, but that he would not rule it out, either.

“If I’m too harsh, they might think, ‘Well, we can’t ever satisfy Grassley,’ ” he said. “So I think they’re feeling their way along, I’m willing to observe as they feel their way along, and I haven’t drawn any conclusions about legislation — except it’s possible.”

And for as long as he says that, leaders at universities nationwide will remain on edge. Grassley, meanwhile, says he will keep tabs on any new endowment spending policies or financial aid packages and hopes schools will reassess, as Yale did, their practices.

“I’m encouraging this self-correcting,” he said. “Soon after the first of the year I’ll be surveying how these trends are going and drawing conclusions at that time about whether legislation needs to be done.”