As a follow-up to the kerfuffle over President Obama's speech at Notre Dame, a story was circulating in conservative Catholic circles last week about the Vatican's supposed veto of three potential U.S. ambassadors because they are pro-choice. Time says it ain't so, but the story wouldn't have gained the traction it did if it wasn't assumed that Obama would send a Catholic to the Holy See, a precedent established by Ronald Reagan.

From one vantage point, it's a positive development that a president could dispatch a Catholic, practicing or not, to represent the United States at the Vatican. Not that long ago, the very idea of an ambassador to the Vatican was controversial, but the easing of anti-Catholicism has rendered the objections to the idea quaint.

Given the role the Vatican plays in world affairs -- sometimes, as with its opposition to the war in Iraq, an unwelcome one from the U.S. perspective -- it makes sense to have a diplomat in what's left of the Papal States. But why should he or she be a Catholic? That assumption is part of the larger and dubious practice of choosing ambassadors with a religious or ethnic affinity to the countries of their posting. The latest example is the new ambassador to Ireland, Pittsburgh Steelers owner Dan Rooney (who admittedly has been involved in worthy efforts to bring peace to Ireland).

Ideally Obama would send a career diplomat to the Vatican, but if he insists on making a political appointment he can avoid the abortion litmus-test problem by naming a Protestant, a Jew, a Muslim -- or an atheist.

Photo: Pope Benedict XVI, leading a prayer Monday. Credit: AP Photo / Andrew Medichini