By Elliott Gotkine
BBC South America correspondent
Ever since John Paul II died, Argentine Archbishop Jorge Mario Bergoglio has been mooted as a possible successor.
Archbishop Bergoglio 'would preserve' John Paul II's legacy
He certainly has the credentials.
The 68-year-old trained chemist and son of a railway worker has been a cardinal since 2001 and is widely seen as being open and compassionate.
He stands out for his humility, living in a modest apartment, rather than his luxury official residence.
"In favour of Bergoglio is his pastoral attitude, as they say in the Church - his relationship with the people," says Leandro Pastor, a philosophy professor at the University of Buenos Aires, who has known Cardinal Bergoglio for 25 years.
"He's a very simple man. He's very austere. And also, I think he's an intelligent man and someone who is very good at communicating."
He impressed fellow prelates in 2001 when he skilfully helped to manage a synod of bishops in Rome.
Buenos Aires' cardinal is also a strong advocate for the poor. And, as a Latin American, he comes from a region which is home to around half the world's billion or so Catholics.
According to Monsignor Osvaldo Musto, who was at seminary with him, the archbishop would also be a good choice in terms of continuity.
"He's as uncompromising as Pope John Paul II, in terms of the principles of the Church - everything it has defended regarding euthanasia, the death penalty, abortion, the right to life, human rights, celibacy of priests. All of this will continue if Bergoglio is made Pope."
Another factor in his favour is that he speaks Italian - the official language of the Church - and that he traces his ancestry back to Italy.
In the event that cardinals struggle to decide whether to maintain a non-Italian papacy or to return to its traditional roots, Jorge Bergoglio could emerge as a choice of compromise.
But when the cardinals do get down to voting, they will also have to consider the Argentine's health.
For the past 20 years, he has lived with only one functioning lung, although he is said to be in good shape.
And then there is the fact that he is a Jesuit.
This order of the Church has never produced a Pope before.
Its members are supposed to avoid ecclesiastical honours and serve the Pope himself.