As church bells pealed, Claire Gillen, a Notre Dame freshman, stood on the stone steps of the Basilica of the Sacred Heart, accusing this fabled Roman Catholic institution of sin and sacrilege.

"It's a scandal," said Gillen, voicing outrage over the university's invitation to President Obama, a supporter of abortion rights, to deliver the commencement address here on May 17.

Some alumni have called the campus, saying they have thrown away their Fighting Irish sweatshirts in disgust. The local bishop, John D'Arcy, has vowed to boycott the graduation ceremony. A visiting high school senior, Halley Chavey, who said she was thrilled just weeks ago to be accepted for admission, said she might reject the offer because the university is hosting "the most pro-abortion president we've ever had."

But for all the high-pitched indignation, the talk among students and faculty on this gothic campus of towering oaks and sculpted saints seems to reveal a strikingly upbeat mood about Obama's visit.

"Most of us are like, 'Wow, the president of the United States is coming,'" said Brett Ensor, a Texas native who belongs to the Knights of Columbus, opposes abortion and voted for the Republican candidate, Sen. John McCain. "What college wouldn't want Obama to come? This is a tremendous honor for us."

Threatened protests of the president's visit -- some conservative groups on campus have promised to stage demonstrations -- have left liberal students, like Max Young, cringing over the portrayal of Notre Dame as insulated and narrow-minded.

"If you can't speak openly at Notre Dame, who's going to want to come here?" said Young, a supporter of abortion rights, who noted that Catholic teaching endorses many of Obama's views, especially when it comes to aiding the poor and immigrants. "President Obama is one of us. He's on our side."

Notre Dame is regarded as an academic powerhouse and conservative Catholic bastion. But in a mock election here in November, Obama defeated McCain among students by about 11 percentage points. He won roughly the same margin of victory among Catholic voters in the election.

About 97 percent of seniors who have sent letters to the school newspaper, The Observer, support Obama as the commencement speaker, said the editor, Jenn Metz. Letters from alumni, however, have overwhelming opposed his appearance.

As foes of abortion, including Randall Terry, make plans to demonstrate against Obama at the commencement, the student newspaper has published an editorial opposing anything that would mar the graduation ceremony.

"Healthy debate is welcomed," the editorial stated. "Photographs of aborted fetuses are not."

The university's president, the Rev. John Jenkins, has insisted that Notre Dame will not withdraw its invitation to Obama, and the White House has sent word that the president, who will be awarded an honorary doctorate of law, is eager to address the graduates. Jenkins has said the invitation shows respect and admiration for the president, but is not an endorsement of his views on abortion, which the church considers an "intrinsic evil."

In addition to Notre Dame, the president has accepted requests to speak at commencement ceremonies at the U.S. Naval Academy and Arizona State University.

Notre Dame routinely invites presidents to speak at graduation. Obama will be the sixth president to deliver the commencement address on the campus, after Dwight D. Eisenhower, Jimmy Carter, Ronald Reagan, George Bush and George W. Bush.

If some students skip the graduation ceremony, or turn their backs on Obama, as some conservative student groups have urged, it would not be the first time Notre Dame graduates have signaled disagreement with a visiting president. When President George W. Bush addressed the commencement in 2001, many students wore armbands signaling their opposition to his support of the death penalty.

But the appearance of Obama, in the view of some Catholic officials, is grounds for a deeper moral battle. Cardinal Francis George of Chicago, the leader of American bishops, has called the invitation of the president "an extreme embarrassment." A prominent professor of philosophy, Ralph McInerny, has characterized the invitation of Obama as "a deliberate thumbing of the collective nose at the Roman Catholic church."

Professors such as Panos J. Antsaklis, on the other hand, warn that a belligerent stand against Obama would portray the school as weak on academic freedom. "If there are ugly protests," said Antsaklis, who teaches electrical engineering, "the world might see Notre Dame as a place that is not open to other ideas."

In the view of the Rev. Richard McBrien, a prominent liberal theologian at Notre Dame, the commotion over Obama centers not on faith, but on politics.

"This crowd," McBrien said, referring to conservative Catholics, "are simply Republicans who are upset that Obama won the election -- and they want to pick a fight."

But to students such as Gillen, it is a matter of religion.

"Abortion is central to the faith," she said, "It's a non-negotiable issue."