By LAURA MECKLER
SOUTH BEND, Ind. -- President Barack Obama, delivering Sunday's commencement address at the University of Notre Dame, called on advocates on both sides of the abortion debate to tone down their rhetoric, discuss the issues without demonizing one another and seek common ground.
The Catholic university's invitation to Mr. Obama and its decision to confer on him an honorary degree sparked protests by anti-abortion advocates, who marched outside the university's gates and flew a banner with a photo of an aborted fetus.
Mr. Obama, who has long supported abortion rights, mentioned the controversy near the start of his address, and returned to deliver his most-extensive public comments on the abortion debate, at least since he began running for president in 2007.
"Maybe we won't agree on abortion, but we can still agree that this heart-wrenching decision for any woman is not made casually. It has both moral and spiritual dimensions," Mr. Obama said.
Early in his remarks, Mr. Obama was interrupted three times by protesters sitting in the back rows of the circular arena. One yelled, "Abortion is murder!" and "You have blood on your hands." The crowd replied by drowning out the protests with, "We are ND! We are ND!" The protesters were escorted out.
"We're not going to shy away from things that are uncomfortable sometimes," the president said, departing from his text.
Mr. Obama urged more than 2,900 graduates, their family, friends and faculty to hold firm to their beliefs and speak out for them. But he said the "ultimate irony of faith is that it necessarily admits doubt."
"This doubt should not push away our faith. But it should humble us. It should temper our passions, and cause us to be wary of self-righteousness," he said.
The invitation to Mr. Obama amplified longstanding tensions between church teachings and academic freedom. Some anti-abortion activists argued that it was wrong to give a platform and an honorary degree to a president who supports abortion rights. Others, including the university's leadership, said it was essential to listen to, and talk with, people of opposing views.
As Mr. Obama entered the university's Joyce Center at the start of the ceremony Sunday, the protests were not immediately visible inside the hall, where the president was greeted with nearly two minutes of cheers and applause. Several graduates had pasted the Obama campaign logo atop their mortar boards.
Mr. Obama's remarks offered no new policy initiatives aimed at reaching out to the anti-abortion forces. And his upcoming appointment to the Supreme Court, who will likely be someone who supports a constitutional right to abortion, could further inflame them.
Since his inauguration, Mr. Obama has signaled that he wants to tone down the abortion debate. Top aides have begun working with people on both sides of the issue to craft mutually agreeable policies to prevent unwanted pregnancies and to support women who choose to have their babies.
Mr. Obama has taken several policy steps that were welcomed by abortion- rights supporters, including easing restrictions on federal funding for international family planning groups and for embryonic stem cell research. In both cases, he chose not to make any public comments, issuing the policy changes in writing. And in both cases, he called on the two sides to seek common understanding.
The Obama administration has also said it was reviewing a Bush policy that allowed health-care providers to opt out of any work activity that offended their consciences, such as scheduling appointments for abortions. Federal law already allows providers to opt out of performing abortions; this regulation offered broader protections.
Mr. Obama said on Sunday that he wanted to work toward "a sensible conscience clause" that was grounded in "clear ethics and sound science, as well as respect for the equality of women."
He acknowledged that there is little common ground on the fundamental question of whether abortion should be legal. "At some level, the views of the two camps are irreconcilable," he said. "Each side will continue to make its case to the public with passion and conviction. But surely we can do so without reducing those with differing views to caricature."
Arriving on campus, Mr. Obama's motorcade did not encounter any of the protests to his visit. The Associated Press reported that, by noon Sunday, more than 200 abortion opponents stood at the school's front gate, many holding signs with statements such as "Shame on Notre Dame" and "Stop Abortion Now." At least five people were led away in handcuffs.
At least 70 Catholic bishops called on the university to rescind the invitation.
The university has conferred honorary degrees on eight other U.S. presidents, and Notre Dame President Rev. John Jenkins told graduates in a letter that the honor doesn't imply that the university supports all of those recipients' policy positions.
Many graduating students said they were excited by Mr. Obama's visit and suggested that most of the agitation was coming from activists outside the university.
"It doesn't take a lot of people to make a big deal," said graduating engineering student Rick Helffrich, 21 years old, of Jacksonville, Fla. "Five people yelling is louder than 20 people saying, `yeah, whatever.' It's cool the president is coming."