Pope Francis, who presided over the Roman Catholic Church and its estimated 1.4 billion followers for 12 years, died April 21.

With 135 cardinals eligible to vote, the coming conclave is set to be the largest in the history of the Catholic Church and one of the most unpredictable in decades.

The papal conclave to replace Pope Francis will begin Wednesday, May 7, the Vatican said on Monday. Cardinals will convene at the Vatican to begin a process of choosing a new pope, who will become the Catholic Church's 267th leader.