All Vatican personnel involved in supporting the upcoming papal conclave will take an oath of secrecy — under penalty of automatic excommunication.

Workers and clerics assisting the dozens of Catholic cardinals set to gather Wednesday to begin voting on the next pope had to swear to never reveal anything about the proceedings or else risk the Church’s gravest punishment: religious banishment. The employees took their oaths in the Papal Chapel.

Support staff for the cardinals who will elect Pope Francis' successor are taking an oath of secrecy on Monday before the conclave starts on Wednesday.

A papal conclave is set to begin in Vatican City starting May 7, during which cardinals from around the world will elect the next leader of the Roman Catholic church. The tradition occurs any time a pope dies or resigns from the office. Pope Francis died April 21, the day after Easter.

Cardinal Robert Prevost, a Chicago native, is getting attention as a potential pope. But scholars say an American pontiff remains highly unlikely.