Cardinals from around the globe will hold a conclave in the Sistine Chapel from next Tuesday to elect a new leader of the world's 1.2 billion Catholics, after "pope emeritus" Benedict XVI's historic resignation.
Cardinals will first celebrate a "Pro Eligendo Romano Pontifice" mass in St Peter's Basilica after which they will file into the chapel under the famous frescoes of Michelangelo for a centuries-old ritual bound by a vow of secrecy.
A pre-conclave meeting of cardinals on Friday "decided that the conclave will begin on Tuesday, 12 March 2013," the Vatican said in a statement.
On the eve of the event, the 115 "cardinal electors" are expected to move into a special residence within the walls of the Vatican, where they will be cut off from the world.
Each cardinal has to swear not to reveal details of the conclave on pain of excommunication. The cardinals will spend the weekend and Monday in last-minute debates over who is the best candidate.
Vatican watchers have suggested the cardinals are split roughly into two groups, between those who think that Italy's Angelo Scola, the Archbishop of Milan, is the man to lead the Church, and others who would prefer a non-Italian in charge.
Among the other names on the rumour mill are Canadian Marc Ouellet, Ghanaian Peter Turkson, US cardinal Sean O'Malley and Luis Antonio Tagle, the Archbishop of Manila.
"In the past two days things have been getting a bit clearer. There are at least half a dozen possible candidates," French cardinal Andre Vingt-trois, the Archbishop of Paris, told AFP in an interview.
In the run-up to the conclave, the Princes of the Church have seized the rare chance of being able to air their grievances against the Vatican, with no new pope to defer to and no old pope to mourn.
Benedict XVI suddenly announced his resignation last month saying he was too old to keep up with a fast-changing modern world, an unprecedented decision in modern Catholic history that has sent shockwaves through the Church worldwide.
The meetings of cardinals that began on Monday are normally something of a formality before the conclave to elect a new pope but this time around they have taken a revolutionary turn.
The closed-door talks are protected by an oath of secrecy, but the voices calling for change have been growing louder after the first papal resignation since the Middle Ages.
Vatican spokesman Federico Lombardi said that the issue of the Roman Curia -- the administration of the Church -- has been brought up frequently.
German cardinal Walter Kasper has been perhaps the most outspoken, telling the Italian daily La Repubblica before a media blackout was imposed that it was time for a "more horizontal government" to shake up the Church hierarchy.
"The Curia must be revolutionised," Kasper said in the interview, adding: "As well as the word reform, there must be a second: transparency."
Cardinals like Kasper had called for time for discussions that could effectively set out an agenda for the new pope but media reports said that many Italian cardinals were getting restless.
Before they cancelled their daily media briefings on Wednesday, the US cardinals said they were also in favour of broader talks on the Church.
"I think that we need to look attentively at the work of the Curia in recent years," said Daniel DiNardo, the archbishop of Galveston-Houston in Texas.
O'Malley, the archbishop of Boston, said: "There is definitely a lot of reflection going on in the Catholic world on the governance of the Catholic Church and how to improve it."
The Curia is the main instrument of Church governance and includes the Secretariat of State, effectively the foreign ministry, as well as an array of pontifical councils and congregations.
While its role has been a subject of often heated debate in the Church for centuries with reformers calling for greater "collegiality", matters have come to a head with the "Vatileaks" scandal.
Benedict's butler Paolo Gabriele last year leaked hundreds of confidential Vatican documents to the press in what he said was an effort to bring greater transparency and reveal the corruption and infighting in the Vatican.
Suspicions have lingered that more Vatican insiders were involved and a top-secret report into the Curia compiled by three cardinals for Benedict XVI has been judged so sensitive that it will only be shown to his successor.
Massimo Franco, a columnist for Italy's top daily Corriere della Sera, said the report was like a "floating mine" around the Sistine Chapel.