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. 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. 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 make-up 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.