Cardinals on Wednesday spent a second day behind Vatican walls to elect a pope, with all eyes on a chimney that will signal when there is a new leader for the world's 1.2 billion Catholics.
The 115 cardinals held a first inconclusive vote in the Sistine Chapel on Tuesday as they began the process of finding a successor to Benedict XVI, who brought a troubled eight-year papacy to an abrupt end by resigning last month aged 85.
Black smoke billowed into the night air above the Vatican, indicating that no one had gained the two-thirds majority needed to become the 266th pope in the first vote.
White smoke -- produced by mixing the smoke from burning ballots with special flares -- would indicate that a new head of the Roman Catholic Church has been chosen.
Pilgrims and the curious huddled under umbrellas to gaze up at the humble chimney pipe that will announce the momentous news -- but no one can predict how long the cardinals will take.
Some knelt to pray, others sat on camping chairs and read passages from the Bible out loud.
"It's the first time I've travelled to the Vatican to see a conclave, but I really felt this time more than any other the world needs the hope a good pope would bring us," said 71-year-old Brazilian priest Giuseppe Almaida.
The atmosphere is laden with suspense as no clear frontrunner has emerged, although conjecture has coalesced around three favourites: Italy's Angelo Scola, Brazil's Odilo Scherer and Canada's Marc Ouellet, all conservatives like Benedict.
"So far there is no majority, but some candidates with little support will fall by the wayside soon," an anonymous cardinal who is too old to vote in this conclave but took part in preliminary meetings told the Italian daily La Stampa.
Some analysts suggest that Benedict's dramatic act -- the first papal resignation in over 700 years -- could push the cardinals to take an equally unusual decision and that an outsider could emerge as a compromise candidate.
Hopes are high in the Philippines for the popular archbishop of Manila, Luis Antonio Tagle, and on the African continent for South Africa's Wilfrid Napier, the archbishop of Durban, but in practice their chances are slim.
Two-thirds of the cardinals are from Europe and North America, and the view among many experts is that only someone with experience of its inner workings can reform the scandal-tainted Vatican bureaucracy, the Roman Curia.
All the "Princes of the Church" were appointed by Benedict or his predecessor and ideological soulmate John Paul II.
Inevitably, comparisons have been made with the conclave that produced Benedict XVI in 2005.
"We went into the Sistine Chapel better prepared" after John Paul II's death following his protracted decline with Parkinson's disease, noted retired cardinal Paul Poupard.
This time, "the cardinals have had to deal with the shock" of Benedict's abrupt abdication, the French prelate told the Italian daily La Repubblica.
In interviews given before the conclave, voting cardinals pointed to new job requirements arising from the problems facing a Church that is struggling in many parts of the world with scandals, indifference and conflict.
"Managerial skills will surely be useful," Vienna Archbishop Christoph Schoenborn told La Stampa.
And in an indication of a faultline between Vatican insiders and those running far-flung dioceses, Nigeria's John Onaiyekan spoke of "new and innovative methods to boost collegiality".
"In this regard there is a lot of room for development," said Onaiyekan, the archbishop of the Nigerian capital Abuja.
-- 'Mahony's fingerprints' --
The scandal of sexual abuse of children by paedophile priests going back decades -- and the cover-up of their actions by senior prelates -- has also cast a long shadow on the Church.
In a reminder of the relentless pace of the scandal, a new report emerged implicating one of the cardinals taking part in the conclave, Los Angeles Archbishop Roger Mahoney, accused of protecting predator priests.
Lawyers said Tuesday that the archdiocese would pay nearly $10 million (7.5 million euros) to four men who alleged they were molested by a former priest in the 1970s.
"Cardinal Mahony's fingerprints were all over the case," lawyer Vince Finaldi told the Los Angeles Times.
Mahony was stripped of church duties by his successor for mishandling claims against dozens of priests.
Modern-day conclaves normally last no more than a few days. Benedict's election in 2005 following the death of John Paul II took just two days.
Cardinal Timothy Dolan of Boston told ABC News on Tuesday that he predicted a result by Thursday.
The cardinals are sworn to secrecy and will be cut off from any contact with the outside world for the duration of the conclave. They eat and sleep in a Vatican residence where windows are locked shut and phones are for internal use only.