VATICAN CITY (AP) - Cardinals from around the globe locked themselves inside the Sistine Chapel on Tuesday to choose a new leader for the world's 1.2 billion Catholics and their troubled church, surrounded by Michelangelo's imposing frescos imagining the beginning and the end of the world.
The 115 scarlet-robed men entered their conclave with a final appeal for unity to heal the divisions that have been exposed by Pope Benedict XVI's shocking resignation and revelations of corruption in the Vatican bureaucracy.
Led by prelates holding a crucifix and candles, the cardinals chanted the Litany of Saints, the hypnotic Gregorian chant imploring the intercession of the saints, as they filed into the chapel and took their oath of secrecy.
With a dramatic closing of the thick double doors and the exhortation "Extra omnes" or "all out," the ritual-filled conclave began beneath Michelangelo's frescoed "Creation" and before his "Last Judgment" - potent images for the task at hand.
Benedict XVI's resignation has thrown the church into turmoil and exposed deep divisions among cardinals grappling with the apparently conflicting needs for a manager to clean up the Vatican's dysfunctional bureaucracy and a pastor who can inspire Catholics at a time of waning faith and growing secularism.
The buzz 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. Other names included Canadian Cardinal Marc Ouellet, who heads the Vatican's powerful office for bishops, and U.S. Cardinal Timothy Dolan, the exuberant archbishop of New York.
In a final appeal before the conclave began, the dean of the College of Cardinals, retired Cardinal Angelo Sodano, appealed for unity within the church, urging the cardinal electors to put their differences aside for the good of the church.
"Each of us is therefore called to cooperate with the Successor of Peter, the visible foundation of such an ecclesial unity," Sodano said. He said the job of pope is to be merciful, charitable and "tirelessly promote justice and peace."
He was interrupted by applause from the pews - not so much from the cardinals - when he referred to the "beloved and venerated" Benedict XVI and his "brilliant" pontificate.
Sitting in the front row was Benedict's longtime aide, Archbishop Georg Gaenswein, who reported that Benedict was watching the proceedings from the papal residence in Castel Gandolfo, according to a Vatican spokesman the Rev. Thomas Rosica.
For over a week, the cardinals have met behind closed doors to try to figure out who among them has the stuff to be pope and what his priorities should be. But they ended the debate on Monday with questions still unanswered, and many cardinals predicting a drawn-out election that will further expose the church's divisions. The conclave proceeds in silence, with no debate.
During the discussions, Vatican-based cardinals defended their administration against complaints that they have been indifferent to the needs of cardinals in the field. At one point on Monday, the Brazilian head of one Vatican office reportedly drew applause for challenging the Vatican No. 2, who has been blamed for most of the bureaucracy's administrative failings.
"Let us pray for the cardinals who are to elect the Roman pontiff," read one of the prayers during the Mass. "May the Lord fill them with his Holy Spirit with understanding and good counsel, wisdom and discernment."
A few hundred people braved thunderstorms and pouring rain to watch the Mass on giant TV screens in St. Peter's Square. A handful knelt in prayer, eyes clenched and hands clasped. They stayed on through the rain, watching the narrow chimney atop the chapel for the first puffs of smoke which signal whether a pope has been elected or not.
In his final radio address before being sequestered, Dolan on Tuesday said a certain calm had taken hold over him, as if "this gentle Roman rain is a sign of the grace of the Holy Spirit coming upon us."
He said he at least felt more settled about the task at hand. "And there's a sense of resignation and conformity with God's plan. It's magnificent," he said during his regular radio show on SiriusXM's Catholic Channel.
Some of the faithful outside alluded to the huge challenge facing the next pontiff.
"It's a moment of crisis for the church, so we have to show support of the new pope," said Veronica Herrera, a real estate agent from Mexico who traveled to Rome for the conclave with her husband and daughter.
Yet the mood was not entirely somber.
A group of women who say they are priests launched pink smoke from a balcony overlooking the square to demand female ordination - a play on the famous smoke signals that will tell the world whether a pope has been elected. Two topless activists from Femen were dragged away from the edge of St. Peter's Square by police as she protested the Vatican's opposition to gay marriage.
And in a bizarre twist, basketball star Dennis Rodman promised to be in St. Peter's Square on Wednesday in a makeshift popemobile as he campaigns for Cardinal Peter Turkson of Ghana to become the church's first black pope.
None of the cardinals will see it, since they will be sequestered inside the Vatican walls. They are allowed to travel only from the Vatican hotel through the gardens to the Sistine Chapel and back until they have elected a pope. No telephones, no newspapers, no television, no tweeting.
The cardinals began the process Tuesday afternoon by filing into the Sistine Chapel. After the doors closed, they heard a meditation by an elderly Maltese cardinal and were then expected to cast their first ballots.
Assuming they vote, the first puffs of smoke should emerge from the chapel chimney by 8 p.m. (1900 GMT; 3 p.m. EDT) - black for no pope, white if a pope has been chosen.
While few people expect a pontiff to be elected on the first ballot, the Vatican was ready: In the Room of Tears off the Sistine Chapel, three sizes of white cassocks hung from a clothes rack. Underneath, seven white shoe boxes were piled, presumably containing the various sizes of the red leather shoes that popes traditionally wear. The room gets its name from the weight of the job thrust upon the new pontiff.
The papal tailor Gammarelli delivered the clothes on Monday to ensure that the newly elected pope could change immediately into papal white as soon as he accepts the election. With the words "Habemus Papam" - or "We have a pope" - the pontiff then appears on the balcony of St. Peter's Basilica to greet the crowd.
The conclave is taking place amid more upheaval and uncertainty than the church has seen in decades: There's no front-runner, no indication how long voting will last and no sense that a single man has what it takes to be pope.
Going into 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 evidence that 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.
Even the American cardinals couldn't agree on whether to expect a short or long conclave.
Cardinal Dolan this week publicly expressed optimism that the election would be wrapped up quickly. And on the eve of the conclave, he wrote a letter to New York priests, saying: "My guess is that we'd have a new Successor of St. Peter by Thursday evening," according to Dolan's spokesman, Joseph Zwilling.
That bullish stance stood in stark contrast with the view of Chicago Cardinal Francis George: His spokeswoman, Colleen Dolan, told The Associated Press that the cardinal suggested it could be a long affair. George raised the possibility that the cardinals may still be meeting by Saturday, when conclave rules require the cardinals to take a break and spend some time in prayer before resuming voting.
The faithful in St. Peter's square were also weighing in on the papal stakes.
"I don't think it's going to be a European pope," said Michael Flueckiger, a 38-year-old caretaker and sacristan of a church in Flamatt, Switzerland. "In Europe sometimes I think we have given away the gift of faith. Many people have lost the faith. They have lost their expectation in God."