President Barack Obama has been briefly¹ heckled as he addressed students at the largest US Catholic university, amid a row over abortion² rights.

奥巴马总统在美国最大的天主教大学发表关于堕胎的演讲之后，遭到简短地质疑。

Obama has mostly played to favourable³ audiences since his election

Anti-abortion activists⁴ have protested against the president's visit to Notre Dame⁵, in Indiana.

Protests and vigils have been held on and around campus, with several people arrested before Mr Obama's speech.

Mr Obama, who received an honorary degree, defended the right to abortion but said the procedure should be rare.

After entering the White House in January the president also quickly moved to reverse（颠倒，逆转） a Bush-era ban on embryonic⁶（胎盘的） stem-cell research, angering many social conservatives.

There are approximately 60 million Roman Catholics in the US, with almost half of them supporting abortion rights, research suggests. Some 42% believe abortion should be illegal.

'Inappropriate'

Wearing the blue robes（长袍） of Notre Dame, Mr Obama was welcomed onto the stage with a lengthy⁷（冗长的，漫长的） ovation⁸（热烈欢迎，大喝彩） from students and staff.

Support for the president's visit was strong among those in the audience, who watched him receive an honorary degree（荣誉学位） before delivering the commencement（开始，毕业典礼）, or graduation, address.

He was interrupted soon after beginning his speech, prompting a majority of those in the audience to cheer the president, who asked for calm and told listening graduates: "We don't do things the easy way."

The AFP news agency said four men heckled（激烈质问） the president, shouting "abortion is murder" and "stop killing⁹ babies" before being escorted（护送） from the auditorium¹⁰（礼堂）.

Mr Obama laid out his views on abortion in clear terms, describing it as "a heart-wrenching（令人心碎的） decision for any woman".

To sustained（持久的） applause, he outlined steps he supported.

"Let's work together to reduce the number of women seeking abortions¹¹ by reducing unintended pregnancies¹², and making adoption¹³ more available, and providing care and support for women who do carry their child to term," he said.

The decision to invite Mr Obama to Notre Dame, the largest Catholic university in the US, has been fiercely criticised.

Many activists and Church leaders have directed their ire（忿怒） at university authorities they accuse of betraying Catholic principles.

"It is clear that Notre Dame didn't understand what it means to be Catholic when they issued this invitation," said Cardinal¹⁴ Francis George, president of the US Conference of Catholic Bishops¹⁶.

Bishop¹⁵ John D'Arcy, of the diocese（主教教区） where Notre Dame is located, said he would boycott¹⁷（抵制，拒绝参加） the graduation for the first time in his 24 years as bishop, the Chicago Tribune reported.

And conservative critics have described the awarding of an honorary degree as "inappropriate".

Avoiding caricatures（讽刺画，漫画）

Addressing his critics indirectly¹⁸, Mr Obama told academics and graduates at Notre Dame that he did not want the debate around abortion to go away.

Conceding that the views of opposing advocates（提倡者，拥护者） were "irreconcilable¹⁹", he said each side would continue to make its case with conviction.

"Surely we can do so without reducing those with differing views to caricature?" he asked.

A strong majority of students were reported to be in favour of the president's visit, but a petition（请愿，祈求） containing some 360,000 names was delivered to the university as a mark of protest.

Overnight, students opposed to abortion rights attended an all-night prayer vigil（值夜） to protest against Mr Obama's visit, and an estimated 200 people attended a prayer session at Alumni Hall Chapel²⁰.

More than 100 protesters gathered and 23 marched onto the campus on Saturday, the Associated Press reported. Police arrested 19 for trespassing²¹（犯罪，侵入）, with four also charged with resisting police.

A university spokesman said none of those arrested were students, AP added.