Faculty and students at the typically placid Catholic University are mounting protests of recent moves by the school president to bar prominent people who have advocated for abortion rights from speaking on campus.

The catalyst for much of the protest -- including petitions, complaint letters and plans for a student sit-in -- was a decision three weeks ago to block an invitation to actor Stanley Tucci to speak at a forum on Italian film because of his involvement with abortion rights organizations.

Many also are complaining about a larger policy to bar political figures of any party in the days before the Nov. 2 election -- frustrating news for student groups that had hoped to bring such speakers as the Republican Party national chairman and a pair of young congressmen to the Northeast Washington campus this fall. School officials said the ban became necessary because the university would appear partisan if it welcomed antiabortion politicians while turning away those from the opposite side.

Now, with many students and secular faculty members complaining that the policy violates academic freedom and open discourse, some say Catholic is poised for its biggest debate in decades. Ernest M. Zampelli, a longtime professor of economics, called it a "watershed event" for a college community that is generally comfortable with its strong influence from the church.

"This is something that people think goes beyond," he said, "and [that] this is where it should stop."

Sarah McGrath, a senior from Rockville Centre, N.Y., who is president of the Undergraduate Student Government, had sharper words.

"Catholic is digging itself into a hole right now," she said. "My concern is that once things like this start happening and become publicized to this magnitude that our degrees won't be worth as much."

University officials say the decisions are rooted in the school's unique relationship with the Catholic Church -- stronger than that of perhaps any other Catholic-affiliated college. Chartered by the Vatican with a governing board dominated by Catholic bishops, the university includes a seminary operated by the Archdiocese of Washington and a college of canon law. Yet most of its students and faculty are in secular programs in the humanities, sciences and professional schools.

School spokesman Victor Nakas said the policy is nothing new -- that the university always has maintained the right to prohibit speakers whose views run counter to those of the church. But he noted that a set of directives issued in July by the United States Conference of Catholic Bishops "added another layer" to the existing policy.

In their statement, the bishops specifically prohibited Catholic institutions from giving "awards, honors and platforms" to those who oppose the church's fundamental positions, particularly that against abortion.

The statement came at the time of a larger debate -- prompted in part by the presidential candidacy of Sen. John F. Kerry (D-Mass.) -- over whether Catholic politicians who favor abortion rights should be denied the sacrament of Holy Communion. Last month, the Archdiocese of New York decided to break with tradition by not inviting the major presidential nominees to its annual Alfred E. Smith Memorial Foundation Dinner, according to news reports, after debating how to deal with Kerry's support of abortion rights.

Meanwhile, organizers of an Italian film festival in the Washington area had started discussions last month with professors at Catholic about hosting an event on campus. One of the suggested speakers was Tucci, a 2003 Tony Award nominee best known for writing, directing and starring in the movie "Big Night," about an Italian restaurant.

But when the university's president, the Very Rev. David M. O'Connell, heard about Tucci's potential involvement, he told administrators that the actor could not attend.

In a memo to faculty members, O'Connell explained that Tucci -- who has lent his star power to events with the national and New York region chapters of Planned Parenthood -- carried "moral baggage . . . [that] stands in direct contradiction to the values and principles upon which this institution was founded. . . ."

Festival organizers agreed to find a different speaker, and the university's School of Arts and Sciences proceeded with plans to sponsor the event. But the decision shocked many faculty members and students, who noted that Tucci had been invited to talk about film, not abortion.

Professors in the Italian and Media Studies departments, which had been scheduled to co-host the event, pulled their support.

"My colleagues and I said we don't want to have anything to do with a censored event," said Lisa Gitelman, an English professor and director of the media studies program.

Last week, senior professors began circulating a protest letter to O'Connell that they said they expect to have most Arts and Sciences faculty of their rank sign within a few days. The letter argues that the principles of academic freedom should allow speakers "by virtue of their academic competence and, by extension, their competence as artists, performers and participants in public life."

And since "few persons in public life agree wholly with Catholic positions," they argued that the bishops' directives could not be applied consistently.

Students in particular are complaining about the decision to ban politicians from campus. College Republicans said they had hoped to bring Republican National Committee Chairman Ed Gillespie -- a Catholic University alumnus -- to campus this fall, and McGrath had been in discussions to bring two young congressmen, a Democrat and a Republican, for a voter registration push.

Student leaders also are circulating petitions on campus. One student group is planning a peaceful daylong sit-in for Wednesday on the lawn of the university's Pryzbyla Center.

Nakas said complaints that the Tucci ban impinges on academic freedom are unfounded. "This was not going to be a scholarly exercise," he said. Tucci "had used his celebrity status to promote abortion rights, and part of the program was he was going to be honored."

As to concerns by students that the ban on politicians robs them of the experience for which they came to Washington, Nakas noted that many students intern on Capitol Hill. "Politics is all around them," he said. "I don't think it's necessary for politicians to come to campus for students to get that experience."

Still, many students noted that Catholic took great pride in hosting a debate between Gillespie and Democratic National Committee Chairman Terry McAuliffe, another alumnus, in March. Nakas said that that event took place before the bishops issued their statement on hosting abortion rights advocates and that it was unclear whether McAuliffe could be invited in the future.

Catholic has experienced other controversies stemming from church policy in recent years, including the denial in April of a request to sponsor and fund a campus chapter of the NAACP because of the civil rights group's support of abortion rights laws and last year's cancellation of a bookstore appearance by Eleanor Holmes Norton, the District's non-voting delegate in Congress, after some students complained about her abortion rights stance.

Yet neither of those actions generated the level of protest seen this fall.

"You come in [to Catholic University] understanding that there will be certain guidelines which you will be expected to follow," said sit-in organizer Danny Junod, a senior from Ashland, Va. "The issue now is that it's just too much."

The Very Rev. David M. O'Connell, Catholic's president, said actor Stanley Tucci carried "moral baggage."Actor Stanley Tucci was not invited to speak at a film forum because of his abortion rights activism.