VATICAN CITY — The cardinals who enter the papal conclave on Tuesday will walk into the Sistine Chapel in a single file, but beneath the orderly display, they are split into competing lineups and power blocs that will determine which man among them emerges as pope. 

The main divide pits the cardinals who work in the Vatican, the Romans, against the reformers, the cardinals who want the next pope to tackle what they see as the Vatican’s corruption, inefficiency and reluctance to share power and information with bishops from around the world. 

But the factions in this conclave do not break along geographical lines, and in fact, they have produced alliances that are surprisingly counterintuitive: the Romans’ top preference appears to be a Brazilian, and the reformers are said to be pushing for an Italian. 

This conclave is far more unpredictable and suspenseful than the last because the church landscape has shifted in the last eight years. The next pontiff must unite an increasingly globalized church paralyzed by scandal and mismanagement under the spotlight in a fast-moving media age. And among the cardinals, there is no obvious single successor to Pope Benedict XVI, who rattled the church by resigning last month at age 85. 

With all of the uproar over Vatican scandals, the Romans are aware that they may fail if they back one of their own, and so they are said to be coalescing behind the Brazilian, Cardinal Odilo Pedro Scherer, the archbishop of São Paulo. 

Cardinal Scherer is of German heritage, but his selection would give the Roman Catholic Church its first pope from Latin America. The region is home to about 40 percent of the world’s Catholics, and the church is staving off challenges there both from surging evangelical churches and a drift toward secularism. 

The reformers, led by the Americans and some influential Europeans, are reportedly uniting around the Italian, Cardinal Angelo Scola, the archbishop of Milan, a popular pastor and an erudite moral theologian. As an Italian, he is familiar with the culture that dominates the Vatican bureaucracy, but he is not a part of it or beholden to it. 

Many cardinals, however, say they are eager for a pope from outside Italy and better yet, from outside Europe, which they hope would energize the world’s 1.2 billion Catholics. 

Other front-runners could easily emerge in what is shaping up to be a fluid contest with ever-shifting alliances and priorities, according to interviews in the past week with church officials, and the scholars and journalists who study the church. 

With the stage truly wide open, the next pope to come out on the balcony to address the crowd in St. Peter’s Square could be a cardinal from Argentina, Canada, Hungary, Mexico, the Philippines or even the United States. 

Whoever he is, he will have to convince his fellow prelates that his gifts as an evangelist and an administrator can move the church past the scandals of child sexual abuse, the Vatican bank, the recent resignation of a cardinal who admitted he had used his own priests for sexual favors, and the so-called VatiLeaks episode in which the pope’s personal papers were stolen and published, revealing bitter infighting in the church’s central administration, known as the Curia.

“The most perceptive cardinals understand,” said Sandro Magister, a Vatican analyst with the weekly magazine L’Espresso, “that the evangelization of the church is obscured by the petty realities that represent the disorder of the Roman Curia.” 

The last conclave eight years ago presented a far simpler scenario. There was one dominant candidate to beat going in, and that was the German cardinal Joseph Ratzinger, the longtime head of the Vatican’s office on doctrine and the close collaborator of the previous pope, John Paul II. He was elected on the conclave’s second day after just four ballots and took the name Pope Benedict XVI. 

 “In 2005, it was, if not Ratzinger, who? And as they got to know him the question became, why not Ratzinger?” said Austen Ivereigh, a writer on Catholicism from England and the former spokesman for the retired Cardinal Cormac Murphy-O’Connor.

The alignments then were animated by theological differences, with the dwindling pool of liberal cardinals backing alternatives to Cardinal Ratzinger whom others might find acceptable. But this time, there are not enough theological liberals among the cardinals to create a viable bloc.

“While there is doctrinal homogeneity between the cardinals,” said Paolo Flores d’Arcais, editor of the liberal Italian journal MicroMega, “the divisions are harsh between those who want change, in particular on issues of pedophilia and the Vatican bank, and the bishops who want to preserve the status quo of the Curia and preserve its power, even though on the surface they all say they want to change.”

The election comes down to the vote count, and with a two-thirds majority required of the 115 voting cardinals, the winner will need 77 votes. The cardinals in the Roman bloc, who work in the Vatican bureaucracy, number only 38 and come not just from Italy but also from other countries.
They, too, are split into rival factions, many church experts say, between those loyal to the secretary of state, Cardinal Tarcisio Bertone, and the dean of the College of Cardinals, Cardinal Angelo Sodano. Cardinal Sodano is beyond the age of 80 and ineligible to vote, and will therefore not be in the conclave in the Sistine Chapel.

However, Mr. Flores d’Arcais said, “They put their differences aside when it comes to blocking anyone who wants to change.”

For the first time, an American could be poised to overcome the conclave’s traditional aversion to a pope from a superpower, though not all analysts agree on this. The most likely contenders are: Cardinal Timothy M. Dolan, the archbishop of New York, known for his exuberant presence and evangelizing skills; and Cardinal Sean Patrick O’Malley of Boston, a Capuchin Franciscan friar, who has a reputation for having calmed the waters in three successive dioceses (Fall River, Mass.; Palm Beach, Fla.; and Boston) torn by child sexual abuse scandals. Both have spoken out in favor of change. 

Gian Guido Vecchi, a journalist who covers the Vatican, said last week in the Italian newspaper Corriere della Sera, “Even if this won’t be the time for the first American pope, it’s difficult to imagine that the pope can be elected without, or even against, them.”
Some cardinals are considered long shots as candidates, but they could still play kingmakers whose endorsements carry great weight. One kingmaker for the reformers is Cardinal Christoph Schönborn, the archbishop of Vienna, a savvy diplomat descended from nobility who studied with Benedict. Cardinal Schönborn supports Cardinal Scola, the archbishop of Milan, according to Carlo Marroni, a Vatican expert for the Italian business newspaper Il Sole 24 Ore.

If neither the Romans nor the reformers have enough votes to elect their front-runners, there are compromise candidates.

One name mentioned even before Benedict’s resignation is that of a Canadian, Cardinal Marc Ouellet. He is a doctrinal conservative who taught philosophy in Colombia and may have support from some Latin American cardinals. But Cardinal Ouellet has spent many years working in the Vatican and has led the department for bishops since 2010. He could be seen as a crossover candidate acceptable to both Romans and reformers.

Another candidate who is attracting a lot of attention is Cardinal Peter Erdo of Hungary, 60, a canon lawyer who despite his relative youth has twice been elected president of the European bishops’ conference. He has also cultivated close ties to African prelates.

Although both Cardinals Ouellet and Erdo are liked by their colleagues, neither can light up a room, church observers point out, which could be a liability at a time when the church needs a pope who can connect with people. 

Nobody can now say reliably who will come out of the conclave as pope, Mr. Flores d’Arcais said, “Today only Nostradamus can make predictions.”

 Ian Austen contributed reporting from Ottawa, and Dan Bilefsky from Budapest.