WASHINGTON — What's the only thing rarer in the White House than a visiting pope? A Roman Catholic president there to greet him.
Pope Benedict on Wednesday became the second pontiff in history to visit the White House.
Yet only one Catholic, John F. Kennedy, has ever been elected president of the United States. And that was nearly half a century ago.
Only two others have even been nominated by a major political party: Democrats Al Smith in 1928, who lost in a landslide to Herbert Hoover, and John Kerry, who lost a close election to President Bush in 2004.
It's a lopsided ratio: Catholics make up about 25 percent of the U.S. population, but just one (2 percent) of the country's chief executives.
By comparison, Episcopalians make up about 2 percent of the population, but 11 (26 percent) of its presidents. Presbyterians make up about 3 percent of the population, but include 10 (24 percent) presidents.
It isn't that Catholics don't like public life or can't win high office.
Catholics are a majority on the Supreme Court, including the chief justice. They constituted 29 percent of the last Congress — the latest one for which a religious count was available — and include 44 percent of the nation's governors.
But they don't win the presidency.
Many Catholics tried this cycle, including Democrats Sen. Joseph Biden of Delaware, Sen. Christopher Dodd of Connecticut, Rep. Dennis Kucinich of Ohio and Gov. Bill Richardson of New Mexico, as well as Republicans Sen. Sam Brownback of Kansas and former Mayor Rudy Giuliani of New York.
None won a single primary.
Anti-Catholic bias? Almost certainly not. Rather, there are several possible explanations.
One, because Catholics have grown in number, moved from Northern, ethnic city neighborhoods and assimilated into mainstream American society, they've escaped the prejudice that bound them to one another before Kennedy, and they've fragmented politically over issues such as abortion.
That helps explain why they're much less likely to coalesce behind a fellow Catholic now; many probably didn't even know so many Catholics were running in this presidential election cycle.
"Many of us in 1950s Catholic homes had an awareness of being persecuted," said John Zogby, a pollster who's studied the Catholic vote. "To some degree, it was a siege mentality. The anti-Catholic history was deep and palpable."
When Kennedy ran, he had to speak to fears that he'd take orders from the pope.
Now, Zogby said, the typical American Catholic is third-, fourth- or fifth-generation American, may not go to church regularly and generally disagrees with the pope on issues ranging from abortion and marriage to war.
In 2004, the first time since 1960 that Catholics saw one of their own on the ballot, they broke for Protestant Bush over fellow Catholic Kerry by 52-47 percent.
Said Zogby: "There is no Catholic vote."
Also, politics changed after Kennedy, and that's made life difficult, particularly for Democrats such as Kerry.
For one thing, the legalization of abortion in 1973 put Democrats who support abortion rights on the spot. That pressure has only grown in recent years, as some bishops have refused Communion to Catholic politicians who support abortion rights.
Perhaps more importantly, the very idea of religion and politics has changed radically since Kennedy's day.
Then, many Americans feared a Catholic president taking orders from the Vatican. Catholic politicians learned from Kennedy not to talk openly about their religion, but rather to emphasize that their political loyalty was to the Constitution, not the pope. In recent years, however, many voters want to know how faith informs the life of a would-be president.
"A whole generation of politicians, particularly Northern Catholics, would give the Kennedy answer," said John Podesta, a former White House chief of staff for Bill Clinton who's now president of the Center for American Progress, a Democratic research center. "But the question was coming from 180 degrees in the other direction."
Some Catholic Democrats such as Rep. Rosa DeLauro of Connecticut have adapted and now talk more about their faith and how it informs their politics.
Others have not.
When Kerry won the Democratic nomination in 2004, he barely mentioned his religion. "People want a moral center," Podesta said. "He reinforced the idea that his faith was thin or nonexistent."