The jeers, boos and insults flew, as caustic as any that angry New Yorkers have hurled inside Madison Square Garden. The objects of derision yesterday, however, were not the hapless New York Knicks, but Senator John McCain, the keynote speaker at the New School graduation, and his host, Bob Kerrey, the university president.

No sooner had Mr. Kerrey welcomed the audience to the university's 70th commencement than the hoots began to rise through the Theater at Madison Square Garden. Several graduates held up a banner aimed at Mr. McCain, an Arizona Republican and likely 2008 presidential candidate, declaring: "Our commencement is not your platform." Other students and faculty members waved orange fliers with the same message.

Mr. Kerrey, a former Democratic senator from Nebraska, was unapologetic yesterday about inviting Mr. McCain, his friend and fellow Vietnam War veteran, to speak. He noted early in his welcoming remarks that there had been intense media coverage of Mr. McCain's graduation speech last week at Liberty University, headed by the Rev. Jerry Falwell, in which Mr. McCain strongly defended the Iraq war.

"Many predicted that his speech today would not receive as friendly a reception," Mr. Kerrey said. "The expectation is that — and that expectation has already been realized — that some of you in this audience will act up to protest the senator's appearance."

The first student speaker, Jean Sara Rohe, 21, said she had discarded her original remarks to talk about Mr. McCain.

"The senator does not reflect the ideals upon which this university was founded," she said, to a roaring ovation. "This invitation was a top-down decision that did not take into account the desires and interests of the student body on an occasion that is supposed to honor us above all."

Noting that Mr. McCain had promised to give the same speech at all of his graduation appearances, Ms. Rohe, who was one of two students selected to speak by university deans, attacked his remarks even before he delivered them.

"Senator McCain will tell us today that dissent and disagreement are our civic and moral obligation in times of crisis, and I agree," she said. "I consider this a time of crisis, and I feel obligated to speak."

She continued, "Senator McCain will also tell us about his strong-headed self-assuredness in his youth, which prevented him from hearing the ideas of others, and in so doing he will imply that those of us who are young are too naïve to have valid opinions.

"I am young, and although I don't profess to possess the wisdom that time affords us, I do know that pre-emptive war is dangerous and wrong," she said.

She added, "Osama bin Laden still has not been found, nor have those weapons of mass destruction."

As Mr. McCain came to the lectern, dozens of students and professors stood and turned their backs on him. Many waved their fliers.

Before his speech, Mr. McCain thanked Ms. Rohe "for that CliffsNotes version of my address."

Mr. McCain seemed uneasy, but stuck to his script and did not acknowledge the barbs. As Ms. Rohe had predicted, he spoke about the importance of civil discourse, and he reiterated his defense of the war.

"I believe the benefits of success will justify the costs and risks," he said. The protests grew louder and more frequent as he spoke. Some graduates walked out. Others laughed. When Mr. McCain returned to policy after briefly quoting Yeats, someone shouted, "More poetry!"

At another point, someone yelled, "We're graduating, not voting!"

The heckling continued when Mr. Kerrey returned to the lectern, with one audience member shouting, "You're a war criminal!"

Mr. Kerrey, a Medal of Honor winner, has admitted to leading a mission that resulted in the deaths of 13 to 20 unarmed civilians.

If Mr. McCain was playing politics, he seemed to be trying to bolster his conservative credentials, with an eye toward the Republican primaries, and not, as some New School students had suggested, trying to gain credibility as a moderate. Aides to Mr. McCain said that they had expected that he would be jeered by a liberal crowd in New York.

And by giving the same speech to graduates at Liberty, Columbia University and the New School, Mr. McCain appeared intent on restoring his reputation as a straight talker, after assertions that he has been kowtowing to conservative Christians ahead of a presidential run. In 2000, Mr. McCain called Mr. Falwell an agent of intolerance.

After yesterday's event, Mr. McCain told reporters he felt "fine" about his reception. "I feel sorry for people living in a dull world where they can't listen to the views of others," he said.

Mr. Kerrey, on stage, had accused the protesters of "heckling from the audience where no bravery is required."

But one graduate, Aisha Nga, 22, of Atlanta, said protesters were not hiding in the crowd. "Bob Kerrey said we weren't very brave, but I think a lot of people who were booing would say it to his face," she said after the ceremony. Like many of her classmates, she wore an orange armband to protest Mr. McCain's presence. In an interview later, Mr. Kerrey praised students for showing restraint. "They could have done all sorts of things under the umbrella of guerilla politics to destroy the event, and they didn't," he said.

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