WASHINGTON -- He was the only president ever to host a pope at the White House when John Paul II came to visit a quarter-century ago and, in many ways, Jimmy Carter shared a powerful spiritual and philosophical affinity for the Polish pontiff. But when the pope is buried at the Vatican this morning, three living U.S. presidents will be in attendance, and Carter will not.

The reason has touched off a classic Washington imbroglio fueled by suspicion, animosity and distrust. When Carter was left off the delegation list assembled by President Bush's White House, Democrats assumed that he was snubbed. The Bush team is angry at what it considers an unfair smear.

Both sides agree that the White House invited Carter and that he ultimately chose not to go; but questions immediately arose as to whether he was genuinely welcome or subtly discouraged from joining the entourage. Both sides have officially denied any dispute and issued instructions to surrogates not to discuss the matter publicly to avoid prolonging a messy sideshow to a solemn event.

White House Chief of Staff Andrew Card called Carter at least twice to invite him to join the delegation. Carter initially accepted. But when Card called back and reported that others were interested in joining the delegation that was limited to five members, the former president withdrew.

One person close to Carter said he believed the final delegation was a strong one and did not require his presence

A senior administration official said Card had no desire to keep Carter out of the delegation. "Andy is sick about the distortion," the official said. "Andy would have thrown somebody else off rather than keep President Carter off."

But partisans without direct knowledge found it hard to accept, especially given the history of bitterness between the Carter and Bush teams.

Carter strongly condemned Bush's war with Iraq when he was awarded a Nobel Peace Prize, then later delivered a sharply critical speech at last year's Democratic National Convention. While Bush lately has forged a relationship with former President Bill Clinton, he has never been close to Carter.