A rabbi who has known Pope Francis for almost 20 years and counts him as a close friend has said the Pope's trip to the Holy Land in May will be a challenging balancing act because of the high expectations of Israelis and Palestinians and of Christians, Jews and Muslims. Rabbi Abraham Skorka, rector of Buenos Aires's Latin American Rabbinical Seminary and co-author with the Pope of the book, On Heaven and Earth, made the remarks during a trip to Rome. Speaking at the Jesuit-run Pontifical Gregorian University about Catholic-Jewish relations in Argentina, the rabbi told reporters the Pope's trip to Jordan, Israel and Palestine will be a "great challenge". He said: "What I expect, ask from God and hope with all my heart is that in a very intelligent way, in a very careful way - because the inhabitants of that region ... have many passions - he is able to leave a message of peace that will inspire a dimension of peace for all," the rabbi said. "Obviously, it won't be easy." "It's easy to imagine the Pope being dragged by his coattails from one place to another because of what he represents and what he means," Rabbi Skorka said. However, he said, the Pope has the strength and charisma to resist manipulation, "and leave a very positive sign". "He won't resolve all the problems - that's impossible," the rabbi said, "but I hope he can leave a sign that can inspire people to peace." The rabbi was in Rome in with a group of Jewish leaders from Argentina. They had a kosher lunch, catered by a Rome restaurant, with Pope Francis at the Domus Sanctae Marthae, where the Pope lives. Rabbi Skorka went back for a private lunch with the Pope.