Vatican City, February 20 - Pope Benedict XVI may issue a document on the rules of the conclave to elect his successor before he steps down as pontiff, Vatican spokesman Father Federico Lombardi said Wednesday. Lombardi said Benedict may issue a 'motu proprio', a document that popes can use to make changes to Church law or procedure. The spokesman did not rule out the possibility that the motu proprio would concern changes so that the conclave could take place earlier than mid-March. The Vatican initially said that the conclave would not take place until 15 to 20 days after Benedict leaves the position on February 28, in accordance with Church rules. But at the weekend Lombardi said the conclave may start earlier, given that the pope has not died, but has quit. Many cardinals are already in Rome and they have begun informal talks about what sort of person the next pope should be. Some clergymen want the conclave to be held earlier to reduce the amount of time the world's 1.2 billion Catholics have to spend without a leader. According to reports, some cardinals are hoping to accelerate proceedings in order to have a new pope installed before Palm Sunday on March 24, so he can preside over the Holy Week services leading up to Easter. "I don't know whether he (Benedict) will deem it necessary or opportune to provide clarifications about the issue of when the conclave starts," said Lombardi. The spokesman said Benedict was considering drafting a motu proprio to harmonize two different documents that govern the period when the papacy is vacant - usually because the previous pontiff has died - and the specifics of the conclave. A Roman scholar on Wednesday suggested that Benedict has the authority to shorten the period of time before the conclave of cardinals meets to elect his successor, for one occasion only. Benedict could issue a one-time decree that would apply only to the upcoming conclave, said Cesare Mirabelli, president emeritus of Italy's Constitutional Court. This would be "an ad hoc measure to shorten the time" which Vatican law says is needed to bring together the conclave, says Mirabelli, who is also a professor of ecclesiastical law at the University of Rome Tor Vergata. The current situation is "exceptional" because a pope has not retired in roughly 600 years and so in this case, cardinals have been given an unusual amount of notice that a replacement must be found, says Mirabelli. Some 117 cardinals under the age of 80 will be eligible to enter the conclave, which will be held in the Sistine Chapel under Michelangelo's famous frescoed ceiling. Just over half of the cardinals who will vote, 61, are European, and Italy is the country with most electors in this conclave, 28. Benedict named 67 of those cardinals and his much-loved predecessor, John Paul II, appointed the rest. Benedict is a doctrinal conservative and so was John Paul. This factor has influenced the makeup of the college of cardinals and experts say it is likely to lead to the next pope being a conservative regarding issues such as ending the ban on women becoming priests and greater acceptance of homosexuality. The resignation of Pope Benedict XVI has thrown new light on the papacy, Cardinal Walter Kasper said in an interview with Italy's leading newspaper Corriere della Sera Wednesday. Kasper, chairman of the Pontifical Council for Promoting Christian Unity, told the daily that "the essence, the nature of the ministry given by Jesus cannot be changed" but "what has changed is the sacred aura around the papacy," that has been slightly lost over the last two centuries. The role of the pope "needs to be rethought," said the 79-year-old cardinal. With the increasing secularization of Europe and many of the world's Catholics "on the other side of the world in the southern hemisphere," for Kasper the next pope should be a man of "charisma who knows how to draw the faithful. A true shepherd of the people, but also a pastor who can lead the Church". The next papacy will be "a new challenge," he said. As excitement mounts over electing a new pope, tourism is surging in Rome, with bookings from France, Germany and elsewhere in Italy leading the way. Expedia.fr reported a 26% rise in French bookings, a 60% hike from Germany and a 115% spike from Italy. The surge started "in the 24 hours after the pontiff announced his resignation" on February 11, the site said. But for those who cannot be in Rome, the Vatican Television Centre (CTV) has said virtually every moment of Pope Benedict XVI's last day as pontiff will be recorded for posterity. The highlight will be when he leaves the Vatican by helicopter to take up temporary residence at the pontifical summer residence at Castel Gandolfo near Rome. "The departure will be a historic event," said Father Edoardo Maria Vigano', CTV's director. Vigano' said the details of precisely how much of the day would be recorded without invading too much Benedict's privacy had not yet been settled. Benedict will move back to a monastery inside the Vatican when renovation work is complete in a few months.