Catholic Church Cardinals will start the conclave that will elect a successor to resigning pope Benedict XVI on Tuesday, the Vatican announced on Friday, DPA reported.
The decision was taken during the General Congregations, a forum for preliminary talks that has been ongoing since Monday.
On Thursday, the last of 115 cardinals allowed to take part in the conclave - those aged under 80 at the time of Benedict XVI's resignation - arrived in Rome, fueling expectations that a decision on the conclave was imminent.
"All 115 of the Eligible electors for the next Pope are now in Rome. Hope date for Conclave is set soon. Your prayers are really needed," US Cardinal Roger Mahony posted on Twitter.
Before the decision was announced, Vatican spokesman Father Federico Lombardi hinted that cardinals still needed a few days before the conclave, because many of them had yet to address the General Congregations.
As of Friday morning, about 100 of 150 cardinals taking part had spoken before the assembly, Lombardi said.
According to Vatican experts writing for Italian newspapers La Repubblica and La Stampa, the current leading contenders for the papacy are Angelo Scola of Italy and Odilo Pedro Scherer of Brazil.
Scola, the 71-year-old Archbishop of Milan, is said to have the backing of US and German cardinals and is seen as a reformist candidate. He has had only limited dealings with the running of the scandal-prone Roman Curia, the Church's "government".
Sandro Magister, another Vatican expert from weekly L'Espresso, cited as a contender Timothy Dolan, the 63-year-old Archbishop of New York, presenting him as the "candidate who represents the impulse in the direction of purification."
Vatican watchers agreed that Scherer, the 63-year-old Archbishop of Sao Paulo, was the leading conservative candidate, as part of a deal that would see the election of a non-European to the papacy and the appointment of a Curia insider as Secretary of State - the Vatican's second-highest position.
Rome-based daily Il Messaggero tipped Cardinal Mauro Piacenza, an arch-conservative who leads the Congregation of the Clergy, for the Secretariat. La Stampa first wrote about a possible Scherer-Piacenza combination on Sunday.
Experts warned that none of the suggested candidates was sure to reach the necessary two-thirds majority to get elected, and a surprise candidate could emerge at the conclave.
The compromise pope, La Repubblica suggested, could be Hungarian Cardinal Peter Erdo, Archbishop of Budapest and leader of the European bishops' conference.