Vatican City ? Bringing their suitcases and personal views on the future of the church, the cardinals who will select the next pope settled in their rooms Sunday in the Vatican hotel that will be their home until the world’s 1.1 billion Roman Catholics have a new leader.

The conclave starts today after the 115 red-robed cardinals join a formal procession into the Sistine Chapel, where efforts to maintain the secrecy of deliberations have included installing jamming devices to foil sophisticated eavesdropping equipment.

But the cardinals’ arrival at the $20 million Domus Sanctae Marthae took them into the imposed isolation of the papal election — which has not lasted longer than five days in the past century but remains an open-ended process. The last conclave in 1978 took eight ballots over three days to choose Pope John Paul II.

“The new pope has already been chosen by the Lord. We just have to pray to understand who he is,” Florence Cardinal Ennio Antonelli told the congregation at St. Andrea delle Fratte, his titular church a short stroll from Rome’s famous Spanish Steps.

The cardinals have much to ponder following the third-longest papacy in history.

This conclave feels the full weight of the church’s modern challenges, including the influence of Islam, competition from evangelical Christians, the fallout from priest sex scandals, the roles of women and the need to reconcile Vatican teachings that ban condom use with worries about AIDS. They also must seek a global pastor with enough charisma to flourish in an image-driven age.

For the first time, credible papal contenders come from at least three distinct regions: Europe, Africa and Latin America.

The rules of the conclave are strict: no phones, television, publications or outside contact. All staff — including cooks, maids, elevator operators and drivers who will shuttle them the few hundred yards from the hotel to the Sistine Chapel — have taken vows of silence.

For the first time ever, cardinals will be allowed to move about Vatican City freely once the voting starts, though they are forbidden to talk to anyone who hasn’t been sworn to secrecy. The penalty is severe — excommunication.

U.S. Cardinal Roger Mahony, of Los Angeles, hands over his robe to his driver as he leaves the North American College in Rome on his way to the Vatican. Cardinals had a few last hours Sunday to confer with aides or pray with faithful before they were required to check-in at the Domus Sanctae Martae at the Vatican, where they will be sequestered during the conclave to elect the next pope.

The Turin daily newspaper La Stampa reported that many cardinals, preparing for a stressful stretch ahead, had packed compact disc players and headphones along with prayer books and their red hats. Other prelates, it reported, brought along favorite snacks.

Italian Cardinal Salvatore Pappalardo, who at 86 is too old to vote, indicated in remarks on Italian state radio Sunday that he believed his younger peers would be looking for a candidate who would be in tune with global problems — particularly issues of justice, peace and even the environment.

“Providence sends a pope (to meet the needs) of every era,” he said.

Conclave rules

The conclave will follow centuries-old rules that were revised by John Paul II in 1996.

This morning, the cardinals will attend a Mass at St. Peter’s Basilica. In the afternoon, they will walk in a procession from the Vatican’s Apostolic Palace to the Sistine Chapel, take the oath of secrecy and listen to a sermon on their sacred duty.

They may hold an initial round of balloting this afternoon, or wait until Tuesday morning to begin voting. In either case, starting Tuesday there are to be four ballots per day, two in the morning and two in the afternoon. This reduces the opportunities for organized politicking.

Instead, judging from past conclaves, cardinals will closely watch the momentum of the vote counts and make individual, on-the-spot decisions as to whether to support, or oppose, any candidate whose vote total begins to surge toward the threshold of 77 votes.

If no one has been elected after three days of balloting, the cardinals can take a daylong break for prayer, discussion and a “spiritual exhortation” by a senior cardinal. Balloting would then resume, with a similar break after every seven rounds of voting.

After the fourth break — which would come on about the 12th day — the rules set by John Paul II allow the cardinals to lower the threshold for election from two-thirds to 50 percent plus one. The pope could then be elected by 58 of the 115 votes, a major departure from tradition.

Another new element comes with this conclave: Bells will ring after a new pope is chosen in an effort to avoid confusion over the color of smoke wafting from the chapel’s chimney. The smoke is black if balloting fails to produce a pontiff and white if a choice is made.