The religion is Roman Catholicism, the most significant in American politics, the ultimate swing vote. Catholics were the heart of the New Deal coalition. They were the Daley machine in Chicago, the Curley machine in Boston, Tammany Hall in New York. They were, and are, a curious mixture: social conservatives and economic moderates. Appalled when the Democrats went countercultural during Vietnam, they began to drift rightward, at least when it came to presidential politics. Jimmy Carter was the last Democrat to win a Catholic majority. Clinton got 43 percent of their support in 1992 (Perot had 20), but Catholics voted overwhelmingly, 57 percent, for Democratic congressional candidates.

That changed dramatically in 1994. For the first time, a majority of Catholics – 52 percent – voted Republican in House and Senate contests. The reason wasn’t difficult to discern: ““They’d become convinced that Bill Clinton was a liberal,’’ says Kate Walsh O’Beirne, who has tracked the Catholic vote for the Heritage Foundation and National Review. Indeed, the president’s approval ratings among Catholics read like a Clinton administration fever chart: 53 percent in January of 1993, 40 percent by the spring of 1994, 33 percent that November. They were turned off by Clinton’s wishy-washy baby-boomer leadership style. (They were also outraged by Joycelyn Elders, who showed disrespect for the Catholic hierarchy.) ““What really upset them was the crime bill,’’ O’Beirne says. ““They didn’t like midnight basketball.’’ This was, many Republicans believed, the great realignment. The Democrats’ working-class majority, more concerned about social than economic issues, had finally jumped ship.

Not quite. The Gingrich Republicans appear to be working overtime to re-alienate the Catholic vote. They have emphasized a straitened, green-eyeshade brand of economic conservatism that doesn’t seem to connect with Catholics, especially when it comes to tinkering, however responsibly, with cherished social programs like Medicare. Meanwhile, the social matters that still cut deep – crime, support for parochial schools and affirmative action (according to a recent poll, 89 percent of Catholic voters oppose preferences for women or minorities) – have been largely ignored. Abortion, by the way, isn’t so important to lay Catholics: they tend to be slightly more pro-life than other Americans, but are profoundly divided on the issue.

And so the Catholic vote has tacked toward a new champion, or a new-old one: Bill Clinton, who – suddenly – enjoys 53 percent support among Catholic voters. ““He’s been working very hard at winning them back,’’ says Michael Ferguson of the Catholic Campaign for America. ““There’s his involvement in Northern Ireland. Very important. And every time he or the First Lady visit a city, they seem to check in on the local bishop.’’ Most important, however, was the State of the Union Message, with its emphasis on social themes – crime (““one strike and you’re out’’ of public housing), sex and violence on television and, of course, uniforms for school children. ““He practically said that every American child should go to parochial school,’’ says William Bennett of Empower America. ““It was a very Catholic speech.''

Clinton, however, remains Clinton. Which means that he could be off tomorrow, stroking any one of the constituencies that helped drive Catholics from the fold – the lifestyle liberals and racial panderers, the teachers’ unions. ““The Catholic vote is very much up for grabs,’’ says Ferguson. It is particularly important in big, closely contested states like Michigan, Pennsylvania and New Jersey (where 50 percent of the electorate may be Catholic). ““You look at those states and you see a slew of Catholic Republican governors – Voinovich in Ohio, Thompson in Wisconsin, Pataki in New York and, especially, Engler in Michigan,’’ says O’Beirne. These are classic Catholic politicians: conservative, but not intolerant; super-patriotic; fiscal tightwads, but not fanatics. ““It would be nice if there were someone like that running for president,’’ O’Beirne says. ““But there isn’t. Dole may come closest – mostly because of the patriotism, the war sacrifice.''

And Buchanan? ““Too harsh,’’ say both Ferguson and O’Beirne: the Catholic vote isn’t an angry vote. But Pat’s is, palpably, the mug of an Irish-American Catholic – with the mind of a very astute politician. And while it seems entirely unlikely that Buchanan is headed for anything more than enhanced lecture fees when the campaign is over, his unexpected lurch toward Love Thy Neighbor, his ““conservatism of the heart,’’ is a thematic adjustment of no small significance in American politics.