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.

While there are a few cardinals seen as front-runners to succeed Pope Francis -- two often mentioned are Italian Cardinal Pietro Parolin and Filipino Cardinal Luis Antonio Tagle -- many of the clerics who will vote have not made up their minds.

All of the 133 cardinals expected to take part in the secret conclave to elect a new pope have arrived in Rome, the Vatican said on Monday, with the race to succeed Pope Francis seen as wide open.

All 133 Catholic cardinals who will vote for a new pope have arrived in Rome, the Vatican said on Monday, two days before they gather in a conclave to elect the next head of the world's 1.4 billion Catholics.