In a surprising move Monday, Pope Benedict XVI changed the rules of the conclave that will elect his successor.

The new rules allow cardinals to move up the start date if all of them arrive in Rome before the usual 15-day transition between pontificates.  

However, Rev. Federico Lombardi, a Vatican spokesman, said the date of the conclave still won't be known until cardinals meet after the Pope's resignation on Thursday. The decision could be made on March 2-4.

Benedict signed a legal document, issued Monday, with some line-by-line changes to the 1996 Vatican law governing the election of a new pope. It is one of his last acts as pope.

The date of the conclave's start is important because Holy Week begins March 24, with Easter Sunday March 31. In order to have a new pope in place for the church's most solemn liturgical period, he would need to be installed by Sunday, March 17 — a tight timeframe if a conclave were to start March 15.

Meanwhile, reports of misconduct from current cardinals continue to splash across the Italian media.

Cardinal Keith O'Brien, Britain's highest-ranking Catholic leader, says he is resigning as archbishop in the wake of misconduct allegations and will be skipping the conclave to elect a successor to Pope Benedict XVI.

O'Brien's resignation comes as calls for Los Angeles Cardinal Roger Mahony's removal from the conclave grow louder because he allegedly covered up sexual abuse by priests.

Based on reporting by the Associated Press.

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