President George H.W. Bush, stands with Pope John Paul II in the papal library at the Vatican, in this May 27, 1989 file photo. (AP Photo/Ron Edmonds, File)

President Jimmy Carter , right, talks with Pope John Paul II at the White House in Washington in this Oct. 6, 1979 file photo. Carter hosted the first White House by a pope. Pope John Paul II was greeted at Andrews Air Force Base outside Washington by Vice President Walter Mondale. His stay at the White House featured 10,000 guests _ split between separate arrival and departure ceremonies on the North and South Lawns. (AP Photo)

President Bush is greeted by Pope John Paul II upon their meeting in his private library at the Vatican, in this June 4, 2004, file photo. In the background is Vatican Secretary of State Cardinal Angelo Sodano. (AP Photo/Osservatore Romano)

Pope Paul VI, left, and President Lyndon B. Johnson are seen during the Pontiff's visit to New York in this Oct. 4, 1965 file photo. The trip presented protocol problems. President Johnson wanted to see him, but the pontiff was a chief of a state not officially recognized by the U.S. The solution: Johnson flew to New York for dinner at the apartment of his friend Arthur Goldberg, the U.S. ambassador to the United Nations, and the pontiff was welcomed to Johnson's suite at the Waldorf-Astoria Hotel the next day. (AP Photo/File)