The cardinals now return to the Vatican's Santa Marta hotel for the night. They return to the Apostolic Palace for Mass Wednesday morning and a new round of voting.
Beginning Wednesday, the cardinals will cast four ballots a day – twice in the morning and twice in the afternoon.
Earlier Tuesday, the 115 cardinals tasked with electing a new pope were locked in the Sistine Chapel, marking the start of conclave.
Conclave voting entails each cardinal writing his choice on a rectangular piece of paper inscribed with the words "Eligo in summen pontificem" — Latin for "I elect as Supreme Pontiff."
Holding the folded ballot up in the air, each approaches the altar and places it on a saucer, before tipping it into an oval urn, as he intones these words: "I call as my witness, Christ the Lord, who will be my judge that my vote is given to the one who, before God, I think should be elected."
After the votes are counted, and the outcomes announced, the papers are bound together with a needle and thread, each ballot pierced through the word "Eligo." The ballots are then placed in a cast-iron stove and burned with a special chemical.
That's when all eyes will turn to the 6-foot-high copper chimney erected atop the Sistine Chapel to pipe out puffs of smoke to tell the world if there's a new pope.
Black smoke means "not yet." White smoke means the 266th pope has been chosen.
Though no pope was chosen on the first day of conclave, the voting will continue until Saturday March 16, when the cardinals will break for a day of prayer and reflection.
Whoever he is, the next pope will face a church in crisis: Benedict spent his eight-year pontificate trying to revive Catholicism amid the secular trends that have made it almost irrelevant in places like Europe, once a stronghold of Christianity. Clerical sex abuse scandals have soured many faithful on their church, and competition from rival evangelical churches in Latin America and Africa has drawn souls away.
On the eve of the vote, cardinals offered wildly different assessments of what they're looking for in the next pontiff and how close they are to a decision. It was evident Benedict XVI's surprise resignation has continued to destabilize the church leadership and that his final appeal for unity may go unheeded, at least in the early rounds of voting.
Cardinals held their final closed-door debate Monday over whether the church needs more of a manager to clean up the Vatican's bureaucratic mess or a pastor to inspire the 1.2 billion faithful in times of crisis. The fact that not everyone got a chance to speak was a clear sign that there's still unfinished business on the eve of the conclave.
"This time around, there are many different candidates, so it's normal that it's going to take longer than the last time," Cardinal Francisco Javier Errazuriz of Chile told The Associated Press.
"There are no groups, no compromises, no alliances, just each one with his conscience voting for the person he thinks is best, which is why I don't think it will be over quickly."
None of that has prevented a storm of chatter over who's ahead.
The buzz in the papal stakes swirled around Cardinal Angelo Scola, an Italian seen as favored by cardinals hoping to shake up the powerful Vatican bureaucracy, and Brazilian Cardinal Odilo Scherer, a favorite of Vatican-based insiders intent on preserving the status quo.
Scola is affable and Italian, but not from the Italian-centric Vatican bureaucracy called the Curia. That gives him clout with those seeking to reform the nerve center of the church that has been discredited by revelations of leaks and complaints from cardinals in the field that Rome is inefficient and unresponsive to their needs.
Scherer seems to be favored by Latin Americans and the Curia. He has a solid handle on the Vatican's finances, sitting on the governing commission of the Vatican bank, as well as the Holy See's main budget committee.
As a non-Italian, the archbishop of Sao Paulo would be expected to name an Italian as secretary of state — the Vatican No. 2 who runs day-to-day affairs — another plus for Vatican-based cardinals who would want one of their own running the shop.
The pastoral camp seems to be focusing on two Americans, New York archbishop Timothy Dolan and Boston archbishop Sean O'Malley. Neither has Vatican experience. Dolan has acknowledged his Italian isn't strong — seen as a handicap for a job in which the lingua franca of day-to-day work is Italian.
Canadian Cardinal Marc Ouellet is well-respected, stemming from his job at the important Vatican office that vets bishop appointments. Less well known is that he has a lovely singing voice and can be heard belting out French folk songs on occasion.
If the leading names fail to reach the 77 votes required for victory in the first few rounds of balloting, any number of surprise candidates could come to the fore as alternatives.
Errazuriz, the cardinal from Chile, said the key isn't so much where the next pope comes from, but what he brings to the papacy.
Cardinals, he told AP, are looking for a pope "who is close to God, has love for people, the poorest, the ability to preach the Gospel to the world and understand the young and bring them closer to God. These are the categories that count."
He argued that Latin America, counting 40 percent of the world's Catholics, is underrepresented in the college of cardinals. "It doesn't have 40 percent of the cardinals," he said.
Austrian Cardinal Christoph Schoenborn, also a leading papal contender, said he was going into the conclave still rattled by the fact that his mentor, Benedict, had resigned.
"It made me cry. He was my teacher. We worked together for over 40 years," Schoenborn said during a Mass late Sunday. Nevertheless, Schoenborn said the cardinals had banded together to face the future.
"It makes us brothers, not contenders," he said. "Such a surprising act has already begun a true renewal."
The Associated Press and Reuters contributed to this report.