BILL CLINTON IS THE only president who attended a Catholic university, and when he welcomed Pope John Paul II to Denver two years ago, he knew to sprinkle his remarks with several "Holy Fathers."
It did not spare Mr. Clinton a lecture, however.
The pope is opposed to abortion, while the president is not; and the pontiff expressed his views forcefully. "America, you are beautiful and blessed in so many ways," he said as the president squirmed. "If you want equal justice for all, and true freedom and lasting peace, then, America, defend life!"
Today Mr. Clinton will again welcome the pope to America, this time at an airport tarmac in Newark, N.J. Each man will make public remarks before traveling to the archdiocesan headquarters.
There they will conduct a one-on-one meeting, and then attend a vespers service at Newark's cathedral. The president's aides are counting on what politicians call good "visuals." But it's not always so simple. In 1993, under a rainy Colorado sky, all the splendor that typifies a visit by the pope was in evidence - as was the historic awkwardness between American presidents and the spiritual leader of the world's largest Christian denomination.
The United States was founded on the principle of religious freedom, but strains of anti-Catholicism run through the nation's history, and the first papal visit didn't occur until Pope Paul VI came to the United Nations in 1964, four years after America elected its first Catholic president.
Before John F. Kennedy, there was Al Smith, a Catholic nominated for president by the Democrats in 1928. Smith was defeated after a campaign in which prominent Protestant clergymen warned from the pulpit that a victory by Smith would turn the White House into a Vatican outpost.
"If you vote for Al Smith," said the pastor of Oklahoma's largest Baptist church, "you're voting against Christ and you'll all be damned."
Forty-four years before, the Rev. Samuel D. Burchard led a delegation that conveyed similar sentiments to Republican presidential nominee James G. Blaine.
"We are Republicans," he said, "and don't propose to leave our party and identify ourselves with the party [Democrats] whose antecedents are rum, Romanism and rebellion."
In this instance, bigotry backfired. Irish-Americans in New York were incensed by the failure of Blaine to repudiate the remark, which Blaine himself later said cost him the presidency.
Kennedy met his critics - and the Catholic issue - head-on, accepting an invitation to appear before the Houston Ministerial Association. "I am not the Catholic candidate for president," Kennedy said. "I am the Democratic Party's candidate for president who happens also to be a Catholic. I do not speak for my church on public matters, and the church does not speak for me."
Appearing the day before at the Alamo, Kennedy had attempted to find out how many Catholics died there. The best his aides could do was a list of Irish names, resulting in one of the most moving sentences of the campaign: "Side by side with Bowie and Crockett died McCafferty and Bailey and Carey," he said. "But no one knows whether they were Catholics or not, for there was no religious test at the Alamo."
A force in politics
Among modern presidents, it is considered folly to bash Catholics, who have emerged as a huge force in electoral politics. The Catholic census counts some 55 million American Catholics, some 30 million of whom are voters. They are not only concentrated in the 10 most populous states - making them even more influential in the electoral college - but they tend not to sit out elections, either.
Jimmy Carter, an evangelical Protestant, filmed his meeting with the pope and used it briefly as a campaign ad. Ronald Reagan subsequently defeated Mr. Carter largely on the strength of "Reagan Democrats," a broad category of voter that included huge numbers of culturally conservative, working-class Catholics.
Mr. Reagan insisted on formally recognizing the Holy See, which the United States hadn't done since 1867. But he also is the president with the distinction of having nodded off during a televised meeting with the pope.
That is not a likely danger for the energetic Mr. Clinton, whose interest in theology was so keen that one of his professors at Georgetown University urged him to become a Jesuit. But history reveals some other potential pitfalls. One recent example was the Clinton administration's advocacy of abortion rights in the months leading up to a population conference in Cairo, Egypt, last year, a role that infuriated the Vatican.
'Genuine affection for the Clintons'
"There is evidence that the pope has genuine affection for the Clintons, but he is a brave person who will say what he believes - and who has serious moral disagreements with this president," said well-known Catholic author Michael Novak.
George Wiegel, president of the Ethics and Public Policy Center, said the trick for Mr. Clinton is to try and keep the discussion on issues - such as the need for more virtue in society - on which they agree.
"He should also, both out of respect for the pope and a sense of propriety regarding his own office, refrain from using the pope as a chip in the American political poker game," Mr. Wiegel added.
But that is often a hard temptation to resist. One prominent Catholic said Raymond Flynn, the former Boston mayor who is Mr. Clinton's representative to the Holy See, is telling friends that he'll have a new job this time next year.
The post? Head of "Catholics for Clinton."
The pope's schedule in the New York area
3 p.m. Arrive at Newark Airport, to be greeted by President Clinton.
5 p.m. Prayer service at Sacred Heart Cathedral, Newark.
9:15 a.m. -- 1 p.m. Visit to the United Nations
5 p.m. Tour by popemobile inside Giants Stadium in New Jersey.
6 p.m. Mass at Giants Stadium.
9 a.m. Tour by popemobile inside Aqueduct Racetrack, Queens.
9:30 a.m. Mass at Aqueduct Raceway.
5 p.m. Tour by popemobile on grounds of St. Joseph's Seminary, Yonkers.
5:15 p.m. Evening prayer and address to seminarians.
9 a.m. Tour by popemobile, Great Lawn of Central Park.
9:30 a.m. Mass on the Great Lawn.
12:15 p.m. Arrive at residence of Cardinal John J. O'Connor.
3:30 p.m. Recitation of rosary in St. Patrick's Cathedral, Manhattan.
5 p.m. Blessing of the offices of the Vatican's mission to the United Nations.
6:30 p.m. Meeting with leaders of other Christian churches, cardinal's residence.
7 p.m. Dinner with bishops of the region, cardinal's residence.
8:30 p.m. Meeting with leaders of the Jewish community, cardinal's residence.