The Rev. John I. Jenkins, president of the University of Notre Dame, laughs with President Barack Obama after introducing him at commencement ceremonies in South Bend, Ind. Obama’s appearance on Sunday was not warmly received by some Notre Dame students and supporters who disagree with the president’s views on abortion and stem cell research.

South Bend, Ind. ? President Barack Obama strode head-on Sunday into the stormy abortion debate and told graduates at America’s leading Roman Catholic university that both sides must stop demonizing one another.

Obama acknowledged that “no matter how much we want to fudge it … the fact is that at some level, the views of the two camps are irreconcilable.” But he still implored the University of Notre Dame’s graduating class and all in the U.S. to stop “reducing those with differing views to caricature. Open hearts. Open minds. Fair-minded words. It’s a way of life that always has been the Notre Dame tradition.”

One of the noisiest controversies of his young presidency flared after Obama, who supports abortion rights but says the procedure should be rare, was invited to speak at the school and receive an honorary degree. “I do not suggest that the debate surrounding abortion can or should go away,” the president said.

The Rev. John Jenkins, Notre Dame’s president, introduced Obama and praised the president for not being “someone who stops talking to those who disagree with him.” Jenkins said too little attention has been paid to Obama’s decision to speak at an institution that opposes his abortion policy.

Ahead of Obama’s address, at least 27 people were arrested on trespassing charges. They included Norma McCorvey, the plaintiff identified as “Roe” in the Roe v. Wade Supreme Court decision that legalized abortion. She now opposes abortion and joined more than 300 anti-abortion demonstrators at the school’s front gate.

More than half held signs, some declaring “Shame on Notre Dame” and “Stop Abortion Now” to express their anger over Notre Dame’s invitation to Obama.

Obama entered the arena to thunderous applause and a standing ovation from many in the crowd of 12,000. But as the president began his commencement address, at least three protesters interrupted it. One yelled, “Stop killing our children.”

The graduates responded by chanting “Yes we can,” the slogan that became synonymous with Obama’s presidential campaign, as well as “We are ND.” Obama seem unfazed, saying Americans must be able to deal with things that make them “uncomfortable.”

The president ceded no ground. But he said those on each side of the debate “can still agree that this is a heart-wrenching decision for any woman to make, with both moral and spiritual dimensions.

“So let’s work together to reduce the number of women seeking abortions by reducing unintended pregnancies, and making adoption more available, and providing care and support for women who do carry their child to term.”

He said he favored “a sensible conscience clause” that would give anti-abortion health care providers the right to refuse to perform the procedure.

Before taking on the abortion issue, Obama told graduates they were part of a “generation that must find a path back to prosperity and decide how we respond to a global economy that left millions behind even before this crisis hit an economy where greed and short-term thinking were too often rewarded at the expense of fairness, and diligence, and an honest day’s work.”

The abortion issue also is front and center as Obama considers potential nominees to fill the vacancy left by the retirement this summer of Justice David Souter. Abortion opponents are determined to see Roe v. Wade overturned, but only four court justices out of nine have backed that position.