with Catholic prelates, look more credible than some that floated around during the last conclave in 2005, according to Chicago Cardinal Francis George.
"All of them I've seen - unlike last time - are in fact good candidates," he told journalists on Thursday evening. "You've done our work for us."
Like other cardinals now in Rome preparing the general congregations, the pre-conclave meetings where they openly discuss the Church's problems and whisper about who should confront them, George declined to name any names.
An informal list of possible candidates is probably emerging, he said, "but it isn't winnowed yet".
One reason the process is so mysterious is that candidates do not announce their ambition and canvassing votes is taboo.
A spoof campaign poster for Ghanian Cardinal Peter Turkson plastered around Rome drew howls of laughter from passers-by who had just voted in Italy's general election at the weekend.
Frontrunners for now
While there are no official candidates, several names are frequently mentioned in Rome as "papabile" (potential pope).
The following list of the names most often cited is alphabetical, not in order of their chances, and may change between now and when the conclave is held in mid-March.
Joao Braz de Aviz (Brazil, 65) brought fresh air to the Vatican department for religious congregations when he took over in 2011. He supports the preference for the poor in Latin America's liberation theology, but not the excesses of its advocates. Possible drawbacks include his low profile.
Brazilian cardinal Joao Braz de Aviz at St Peter's basilica at the Vatican. (AFP files)
Timothy Dolan (USA, 63) became the voice of US Catholicism after being named archbishop of New York in 2009. His humor and dynamism have impressed the Vatican, where both are often missing. But cardinals are wary of a "superpower pope" and his back-slapping style may be too American for some.
Cardinal Timothy Dolan, Archbishop of New York, at St. Patrick's Cathedral in New York City. (AFP)
Peter Erdo (Hungary, 60) ranks as a possible compromise candidate if the conclave's European majority do not back an Italian but are wary of a pope from overseas. His two terms as head of a European bishops council and strong links with African church leaders shows strong support among two important groups.
Archbishop of Esztergom-Budapest, Hungarian Peter Erdo in Esztergom, Hungary. (AFP)
Sean O'Malley (USA, 68) has been touted as a "clean hands" candidate since he was named to three U.S. dioceses in a row to settle sexual abuse scandals. Appointed to Boston in 2003 after a major crisis there, he sold off archdiocesan properties and prompted protests by closing down little-used churches.
Cardinal Sean O'Malley at The Chapel Pastoral Center in Braintree, Massachusetts. (AFP)
Marc Ouellet (Canada, 68) is effectively the Vatican's top staff director as head of the Congregation for Bishops. He once said becoming pope "would be a nightmare". Though well connected within the Curia, the widespread secularism of his native Quebec could hurt him and even friends say he is not charismatic.
Canadian archbishop Marc Ouellet at St Peter's basilica at the Vatican. (AFP)
Gianfranco Ravasi (Italy, 70) has been Vatican culture minister since 2007 and represents the Church to the worlds of art, science, culture and even to atheists. This profile could hurt him if cardinals decide they need an experienced pastor rather than another professor as pope.
President of the Pontifical Council for Culture since 2007, Cardinal Gianfranco Ravasi, in Rome. (AFP)
Leonardo Sandri (Argentina, 69) is a "transatlantic" figure born in Buenos Aires to Italian parents. He held the third-highest Vatican post as its chief of staff in 2000-2007. But he has no pastoral experience and his job overseeing eastern churches is not a power position in Rome.
Argentine Cardinal Leonardo Sandri at the Vatican. (AP)
Odilo Scherer (Brazil, 63) ranks as Latin America's strongest candidate. Archbishop of Sao Paulo, largest diocese in the largest Catholic country, he is conservative in his country but would rank as a moderate elsewhere. The rapid growth of Protestant churches in Brazil could count against him.
Brazilian Cardinal Odilo Pedro Scherer speaks during a press conference at Se Cathedral in Sao Paulo, Brazil. (AFP)
Christoph Schoenborn (Austria, 67) is a former student of Pope Benedict with a pastoral touch the pontiff lacks. The Vienna archbishop has been seen as papal material since editing the catechism in the 1990s. But some cautious reform stands and strong dissent by some Austrian priests could hurt him.
Austrian Cardinal Christoph Schoenborn looks on after a press meeting in Vienna. (AFP)
Angelo Scola (Italy, 71) is archbishop of Milan, a springboard to the papacy, and is many Italians' bet to win. An expert on bioethics, he also knows Islam as head of a foundation to promote Muslim-Christian understanding. His dense oratory could put off cardinals seeking a charismatic communicator.
Cardinal Angelo Scola in Milan's Duomo cathedral. (AFP)
Luis Tagle (Philippines, 55) has a charisma often compared to that of the late Pope John Paul. He is also close to Pope Benedict after working with him at the International Theological Commission. While he has many fans, he only became a cardinal in 2012 and conclaves are wary of young candidates.
Filipino Roman Catholic Cardinal Luis Antonio Tagle, the Archbishop of Manila, in Manila. (AP)
Peter Turkson (Ghana, 64) is the top African candidate. Head of the Vatican justice and peace bureau, he is spokesman for the church's social conscience and backs world financial reform. He showed a video criticizing Muslims at a recent Vatican synod, raising doubts about how he sees Islam.
Ghanaian Cardinal Peter Kodwo Appiah Turkson during an interview in Rome. (AP)