VATICAN CITY -- Cardinals from around the world gather Tuesday in a conclave to elect a new pope following the stunning resignation of Benedict XVI.
In 2005, it took only 24 hours for them to select a pope. Some are saying they will name a new pope by Friday.
In the secretive world of the Vatican, there is no way to know who is in the running, and history has yielded plenty of surprises.
Yet several names have come up repeatedly as strong contenders.
Here is a look at who they are:
CARDINAL ANGELO SCOLA: Scola is seen as Italy's best chance at reclaiming the papacy, following back-to-back pontiffs from outside the country that had a lock on the job for centuries. He's also one of the top names among all of the papal contenders.
Scola, 71, has commanded both the pulpits of Milan's Duomo as archbishop and Venice's St. Mark's Cathedral as patriarch, two extremely prestigious church positions that together gave the world five popes during the 20th century. Scola was widely viewed as a papal contender when Benedict was elected eight years ago. His promotion to Milan, Italy's largest and most influential diocese, has been seen as a tipping point in making him one of the leading papal candidates. He is known as a doctrinal conservative who is also at ease quoting Jack Kerouac and Cormac McCarthy.
CARDINAL ODILO SCHERER: Scherer is known for prolific tweeting, appearances on Brazil's most popular late-night talk show and squeezing into the subway for morning commutes. Brazil's best hope to supply the next pontiff is increasingly being touted as one of the top overall contenders. At the relatively young age of 63, he enthusiastically embraces all new methods for reaching believers, while staying true to a conservative line of Roman Catholic doctrine and hardline positions on social issues such as rejection of same-sex marriage.
Scherer joined Twitter in 2011 and in his second tweet said: "If Jesus preached the gospel today, he would also use print media, radio, TV, the Internet and Twitter. Give Him a chance!" Scherer became the Sao Paulo archbishop in 2007 and was named a cardinal later the same year.
CARDINAL MARC OUELLET: Canada's Ouellet once said that being pope "would be a nightmare." He would know, having enjoyed the confidence of two popes as a top-ranked Vatican insider. His high-profile position as head of the Vatican's office for bishops, his conservative leanings, his years in Latin America and his work in Rome as president of a key commission for Latin America all make him a favorite to become the first pontiff from the Americas.
But the qualities that make the 68-year-old popular in Latin America - home to the world's biggest Catholic population - and among the cardinals who elect the pope have contributed to his poor image in his native Quebec, where ironically he was perceived during his tenure as archbishop as an outsider parachuted in from Rome to reorder his liberal province along conservative lines.
CARDINAL PETER ERDO: Erdo is the son of a deeply religious couple who defied communist repression in Hungary to practice their faith. And if elected pope, the 60-year-old would be the second pontiff to come from eastern Europe - following in the footsteps of the late John Paul II, a Pole who left a great legacy helping to topple communism. A cardinal since 2003, Erdo is an expert on canon law and distinguished university theologian who has also striven to forge close ties to the parish faithful. He is increasingly seen as a compromise candidate if cardinals are unable to rally around some of the more high-profile figures like Scola or Scherer.
CARDINAL GIANFRANCO RAVASI: Ravasi, the Vatican's culture minister, is an erudite scholar with a modern touch - just the combination some faithful see as ideal for reviving a church beset by scandal and a shrinking flock. The 70-year-old is also one of the favorites among Catholics who long to see a return to the tradition of Italian popes. The polyglot biblical scholar peppers speeches with references ranging from Aristotle to late British diva Amy Winehouse. Ravasi's foreign language prowess is reminiscent of that of the late globetrotting John Paul II: He tweets in English, chats in Italian and has impressed his audiences by switching to Hebrew and Arabic in some of his speeches.
CARDINAL PETER TURKSON: Often cast as the social conscience of the church, Ghana's Turkson is viewed by many as the top African contender for pope. The 64-year-old head of the Vatican's peace and justice office was widely credited with helping to avert violence following contested Ghanaian elections. He has aggressively fought African poverty, while disappointing many by hewing to the church's conservative line on condom use amid Africa's AIDS epidemic. Turkson's reputation as a man of peace took a hit recently when he showed a virulently anti-Islamic video, a move now seen as hurting his papal prospects. Observers say those prospects sank further when he broke a taboo against public jockeying for the papacy - saying the day after Benedict's resignation announcement that he's up for the job "if it's the will of God."
CARDINAL TIMOTHY DOLAN: Dolan, the 63-year-old archbishop of New York, is an upbeat, affable defender of Catholic orthodoxy, and a well-known religious figure in the United States. He holds a job Pope John Paul II once called "archbishop of the capital of the world." His colleagues broke with protocol in 2010 and made him president of the U.S. Conference of Catholic Bishops, instead of elevating the sitting vice president as expected. And during the 2012 presidential election, Republicans and Democrats competed over which national political convention the cardinal would bless. He did both. But scholars question whether his charisma and experience are enough for a real shot at succeeding Benedict.
CARDINAL JORGE MARIO BERGOGLIO: Bergoglio, 76, has spent nearly his entire career at home in Argentina, overseeing churches and shoe-leather priests. The archbishop of Buenos Aires reportedly got the second-most votes after Joseph Ratzinger in the 2005 papal election, and he has long specialized in the kind of pastoral work that some say is an essential skill for the next pope. In a lifetime of teaching and leading priests in Latin America, which has the largest share of the world's Catholics, Bergoglio has shown a keen political sensibility as well as the kind of self-effacing humility that fellow cardinals value highly. Bergoglio is known for modernizing an Argentine church that had been among the most conservative in Latin America.
CARDINAL LEONARDO SANDRI: Leonardo Sandri, 69, is a Vatican insider who has run the day-to-day operations of the global church's vast bureaucracy and roamed the world as a papal diplomat. He left his native Argentina for Rome at 27 and never returned to live in his homeland. Initially trained as a canon lawyer, he reached the No. 3 spot in the church's hierarchy under Pope John Paul II, the zenith of a long career in the Vatican's diplomatic service ranging from Africa to Mexico to Washington. As substitute secretary of state for seven years, he essentially served as the pope's chief of staff. The jovial diplomat has been knighted in a dozen countries, and the church he is attached to as cardinal is Rome's exquisite, baroque San Carlo ai Catinari.
CARDINAL LUIS ANTONIO TAGLE: Asia's most prominent Roman Catholic leader knows how to reach the masses: He sings on stage, preaches on TV, brings churchgoers to laughter and tears with his homilies. And he's on Facebook. But the 55-year-old Filipino's best response against the tide of secularism, clergy sex abuse scandals and rival-faith competition could be his reputation for humility. His compassion for the poor and unassuming ways have impressed followers in his homeland, Asia's largest Catholic nation, and church leaders in the Vatican. Tagle's chances are considered remote, as many believe that Latin America or Africa - with their faster-growing Catholic flocks - would be more logical choices if the papal electors look beyond Europe.
CARDINAL CHRISTOPH SCHOENBORN: Schoenborn is a soft-spoken conservative who is ready to listen to those espousing reform. That profile could appeal to fellow cardinals looking to elect a pontiff with the widest-possible appeal to the world's 1 billion Catholics. His Austrian nationality may be his biggest disadvantage: Electors may be reluctant to choose another German speaker as a successor to Benedict. A man of low tolerance for the child abuse scandals roiling the church, Schoenborn, 68, himself was elevated to the upper echelons of the Catholic hierarchy after his predecessor resigned 18 years ago over accusations that he was a pedophile.
CARDINAL MALCOLM RANJITH: Benedict XVI picked the Sri Lankan Ranjith to return from Colombo to the Vatican to oversee the church's liturgy and rites in one of his first appointments as pope. The choice of Ranjith in 2005 rewarded a strong voice of tradition - so rigid that some critics regard it even as backward-looking. Ranjith in 2010 was named Sri Lanka's second cardinal in history. There are many strikes against a Ranjith candidacy - Sri Lanka, for example, has just 1.3 million Catholics, less than half the population of Rome. But the rising influence of the developing world, along with the 65-year-old's strong conservative credentials, helps keep his name in the mix of papal contenders.
CARDINAL ANDRES RODRIGUEZ MARADIAGA: To many, Maradiaga embodies the activist wing of the Roman Catholic Church as an outspoken campaigner of human rights, a watchdog on climate change and advocate of international debt relief for poor nations. Others, however, see the 70-year-old Honduran as a reactionary in the other direction: Described as sympathetic to a coup in his homeland and stirring accusations of anti-Semitism for remarks that some believe suggested Jewish interests encouraged extra media attention on church sex abuse scandals. Maradiaga, the archbishop of Tegucigalpa, is among a handful of Latin American prelates considered to have a credible shot at the papacy.
CARDINAL ANGELO BAGNASCO: The archbishop of Genoa, Bagnasco also is head of the powerful Italian bishops' conference. Both roles give him outsized influence in the conclave, where Italians represent the biggest national bloc, and could nudge ahead his papal chances if the conclave looks to return the papacy to Italian hands. At 70 years old, Bagnasco is seen as in the right age bracket for papal consideration. But his lack of international experience and exposure could be a major liability.
CARDINAL SEAN PATRICK O'MALLEY: As archbishop of Boston, O'Malley has faced the fallout from the church's abuse scandals for nearly a decade. The fact he is mentioned at all as a potential papal candidate is testament to his efforts to bring together an archdiocese at the forefront of the abuse disclosures. Like other American cardinals, the papal prospects for the 68-year-old O'Malley suffer because of the accepted belief that many papal electors oppose the risk of having U.S. global policies spill over, even indirectly, onto the Vatican's image. O'Malley is among the most Internet-savvy members of the conclave.