He who enters the Conclave as Pope, leaves it as a Cardinal

So the Italians have a word to describe a cardinal that is good Pope material. He is called Papabile. Now here is what Wikipedia has to say about the term Papabile:

PAPABILE (Italian pronunciation: [paˈpaːbile], pl. papabili) is an unofficial Italian term first coined by Vaticanologists and now used internationally in many languages to describe a Catholic man, most often a cardinal, who is thought a likely or possible candidate to be elected pope. A literal English translation would be "pope-able" or "one who might become pope".

In some cases the cardinals will choose a papabile candidate. Among the papabili cardinals who have been elected pope are Eugenio Pacelli (Pius XII), Giovanni Battista Montini (Paul VI), and Joseph Ratzinger (Benedict XVI). However, at times the College of cardinals elect a man who was not considered papabile by most Vatican watchers. In recent years those who were elected pope though not considered papabili include John XXIII, John Paul I, and John Paul II. There is a saying among Vaticanologists: "He who enters the conclave as pope, leaves it as a cardinal."

The list of papabili changes as cardinals age. For instance Carlo Maria Martini was thought to be papabile until he retired from his see upon reaching 75 years of age. The list of papabili in the 2005 papal conclave shows who was considered papabile at the death of John Paul II. As Pope Benedict XVI was one of the oldest men on the list, most men on the list remain among his potential successors.