BOB ABERNETHY, anchor: The debate over abortion and Catholic politicians has focused on Senator John Kerry and his campaign for the presidency, but it affects all Catholic public officials who are pro-choice. A panel of Catholic bishops is studying what the Church's response should be. It is led by Cardinal Theodore McCarrick of Washington, DC, who says he would not be comfortable denying them the Eucharist. A new ad campaign by an antiabortion Catholic group said McCarrick's words would be "cold comfort for the 1.3 million babies surgically aborted every year."

Now, correspondent Lucky Severson looks at the challenges faced by Catholic politicians, past and present.

LUCKY SEVERSON: In October 1960, John Fitzgerald Kennedy, the Catholic candidate for president, drew the line as to how he would deal with his religion as president.

JOHN F. KENNEDY: I am not the Catholic candidate for president. I am the Democratic Party's candidate who happens also to be Catholic. I do not speak for my church on public matters and the Church does not speak for me.

SEVERSON: Now, over 40 years later, another Catholic presidential candidate with the same initials -- John Forbes Kerry -- is under intense pressure to support his church's position or be punished.

JOSEPH STARRS (American Life League): If Senator Kerry and company insist on supporting abortion then they should have the moral integrity not to receive Holy Communion. To do otherwise is an arrogant repudiation of the church they claim membership in.

SEVERSON: Joseph Starrs is with a conservative Catholic organization called the American Life League. He is serving notice, not only to candidate John Kerry but to every other Catholic lawmaker who doesn't vote against abortion -- threatening denial of an important sacrament through which Catholics receive grace.

The league's views are less forgiving than those of many Catholics. But the notion of holding politicians accountable is gaining momentum. Ambassador Raymond Flynn says it's about time so-called "cafeteria Catholics" toe the line. Flynn is a former mayor of Boston and was the U.S. ambassador to the Vatican during the Clinton administration.

RAY FLYNN (Former U.S. Ambassador): I've heard the Holy Father on a number of occasions say that Catholics as elected officials must accept political responsibility, they must be faithful Catholics, and quite frankly, I agree with him.

SEVERSON: Another prominent Catholic with quite a different view: former New York Governor Mario Cuomo.

MARIO CUOMO (Former Governor, New York): One of the reasons the country was created was for me to be free to be a Catholic and you to be whatever you wish to be. In order to protect that freedom of religion, you must be careful not to intrude upon other people's freedom of religion. For me to be protected in my right to be against abortion and against contraceptives, I have to make sure not to tread upon your right not to believe in those things, because if I can impose my religion on you, you can impose your religion on me.

SEVERSON: Much has changed since the 1960 JFK speech. The Supreme Court has legalized abortion. And antiabortion forces are gaining votes and political influence. But of the 150 Catholics in Congress, more than 70 have cast pro-choice votes.

Mr. FLYNN: You can't say you are a Catholic on Election Day and then go up to the statehouse, city hall, the Congress, and vote any way you want. You have to be accountable.

SEVERSON: Until recently, the Church has often looked the other way when politicians voted pro-choice -- until last year, when a Vatican doctrinal decree declared that Catholic lawmakers have a "grave and clear" obligation to oppose any law that attacks human life. Some American Church leaders, including the newly appointed Archbishop of St. Louis, Raymond Burke, interpreted the pronouncement as an ultimatum. He said he would deny Communion to pro-choice lawmakers, including John Kerry.

This is Burke, earlier this year, on Catholic television when he was still bishop of La Crosse, Wisconsin.

Reverend RAYMOND BURKE (Archbishop, St. Louis): Any legislator who is publicly supporting laws which favor abortion or euthanasia may not present himself or herself for Holy Communion.

Mr. CUOMO: Do I, as a Catholic, think it's extreme? Of course I do. The consecration, the making of the bread and wine into the body and blood of our Savior, is the ultimate religious act for Catholics. And participating in it is the ultimate participation. It's the reason I wrote the speech in 1984 on this subject.

SEVERSON: It was, for the time, a defining speech responding to a veiled public threat of possible excommunication from then Cardinal John O'Connor. It was directed at Cuomo and vice presidential candidate Geraldine Ferraro.

Mr. CUOMO: It went through me like a blade, and that's when I did something that no Catholic did before.

(Giving Speech): The Catholic public official lives the political truth most Catholics, throughout most of American history, have accepted and insisted on: the truth that to assure our freedom, we must allow others the same freedom, even if occasionally it produces conduct by them that we would hold to be sinful.

SEVERSON: That was 20 years ago. If Cuomo were governor today, he might be denied Communion.

Rev. BURKE: I'm not telling these legislators how to vote, I'm telling them how to form their conscience as Catholics. And they have to draw their conclusions from that, and if they want to remain a good Catholic, they know how they should act.

SEVERSON: But not all Catholics support the archbishop's edict, including Raymond Flynn, an advocate for more discipline.

(To Mr. Flynn): Do you think that these politicians should be denied Communion?

Mr. FLYNN: No, I don't think that's a decision that I should make and I don't believe that should happen, but I would say, however, that there should be some level of discipline.