Pope Francis, supreme pastor to almost 1.5 billion Catholics, died on Monday at the age of 88.

The papal throne, which now sits vacant, is approximately two-thousand years old. In the past, popes crowned kings and emperors. In the present, they hold audiences with royalty, presidents, and prime ministers. At all times, they have been the successor of St. Peter and a living point of unity for believers.

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The cultural weight of the papacy is captured in the pontiff’s full list of titles: Bishop of Rome, Vicar of Jesus Christ, Successor of the Prince of the Apostles, Supreme Pontiff of the Universal Church, Patriarch of the West, Primate of Italy, Metropolitan Archbishop of the Roman Province, Sovereign of the Vatican City State, Servant of the Servants of God.

Now, without its monarch, the Western world’s most powerful religious institution is sailing into unknown waters. At the helm is a group of a scarlet-clad churchmen burdened with deciding from amongst themselves who can bear the burden of the papal tiara.

A period of mourning has begun at the Vatican and in Catholic churches around the world. The faithful pause to remember the life of modernity’s most unlikely pontiff and look ahead in anticipation of his successor. This is a time known as sede vacante (Latin: the chair [of St. Peter] being empty).

During this period, the pope’s supreme authority is transferred in a limited capacity to the College of Cardinals, often referred to as the “princes of the church.”

After Pope Francis is buried, many of these men will chant prayers as they enter the Sistine Chapel. There, they will hold the conclave (Latin: “[locked] with a key”), an election to determine the next pope.

The trappings of the conclave are a perennial fascination. Cardinals clad in choir dress march solemnly to their quarters. The door to the chapel is locked. Spectators watch the chimney for smoke indicating whether each ballot was successful. White smoke arising from the chimney of the chapel means a new pope has been elected.

All of this is ornamentation on an election that is as simple as it is ancient — multiple rounds of voting each day until two-thirds agree. All voting is secret, and none can leave until it is finished. The cardinals can hypothetically elect any Catholic man to the position, but in the modern day it is invariably one of their own.

Approximately 135 cardinals are eligible to take part in the conclave. Of those, about 108 were appointed by Pope Francis. Cardinals over the age of 80 do not have voting privileges but can meet with the others in the meetings ahead of the conclave.

Predicting the next pontiff is often a futile endeavor. The personal discernment of individual cardinals and the factions that can form ahead of a conclave are usually understood only by those participating. At various times throughout history, the conclave has been skewed by political, ethnic, and even financial interests seeking to stack the deck for the next pope in their own favor.

Well into the 20th century, the vast majority of cardinals were Catholic bishops based in mainland Europe. Italians wielded a strong influence in the conclaves and usually picked each pontiff from among their own countrymen.

The 1978 election of Pope John Paul II, a Polish cardinal who went on to become a saint, came after seven Italians occupied the Holy See across 70 years.

As recently as Pope Benedict XVI’s election in 2005, geographic voting blocs were formed ahead of time to marshal votes and push agendas.

Pope Francis told Spanish journalist Javier Martínez-Brocal that he was targeted by a progressive-minded alliance in the College of Cardinals known as the St. Gallen Group while still Cardinal Jorge Bergoglio. The group of European liberal bishops allegedly attempted to use Bergoglio as a block against Benedict’s election until the Argentinian found out and protested.

The last several popes have expanded the scope and diversity of background in the College of Cardinals, including prelates from more distant countries to bring greater perspective to a Catholic Church that had become too focused on its home continent.

Pope Francis continued this trend and drastically shuffled the balance of power within the College of Cardinals.

At present, there are over 250 cardinals from over 90 countries across the globe, approximately 135 of which are voting age.

They vary drastically in cultural background and theological disposition. They are largely unfamiliar with one another on a personal level. If geographic or interpersonal voting blocs have been formed, they are unknown.

Each cardinal carries with him a deeply personal relationship with the Catholic Church reflective of factors such as their country, their ethnicity, and their formation as a priest. Africans are, on average, much more traditionalist than their fellow princes of the church. Europeans remain largely more liberal in their theology, as do South Americans. Cardinals from North America are a mixed bag.

Some cardinals want to be crowned but fail to win the college over. Others want to run away from the papacy as fast as they can, but their fellow cardinals force it upon them.

Vaticanologists and Catholic journalists often keep informal databases of which cardinals are considered papabile, or possible successors to the office. Guessing which cardinal will be selected to sit on the Holy See has always been tricky, but the diffusion of cardinal positions and breakdown of historic blocs makes ranking candidates even more questionable.

Cardinal Pietro Parolin, the Vatican Secretary of State, is the most obvious candidate. His extensive curriculum vitae is packed with diplomatic work and administration experience. His views seem to align quite close with those of Pope Francis, making him a safe choice for those seeking to avoid a chaotic transition. Parolin is also Italian, commonly considered a plus when one values stability in the papacy.

Other prospects considered in line with Pope Francis’ worldview include the late pontiff’s special peace envoy, Cardinal Matteo Zuppi, and Cardinal Luis Tagle, a Filipino who would be the first Asian pope.

Cardinal Peter Erdo from Hungary is seen as among the most likely conservative candidates. He is theologically rigid and focuses heavily on doctrinal adherence, but has shown deference to the Holy See even when seemingly out of step with its decisions. He is known as a private leader who avoids unnecessary spotlight and has largely dodged the question of a possible pontificate.

Some Catholic archconservatives cling to the hope of traditionalists such as Cardinal Robert Sarah from French Guinea and Cardinal Raymond Burke from the United States. Both are considered unlikely to be chosen due to their high-profile disagreements with the liberal wing of the college, but stranger outcomes have happened.

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Patriarch of Jerusalem Cardinal Pierbattista Pizzaballa has emerged as a dark horse candidate due to his widely-applauded handling of the Israel-Hamas conflict. He was elevated to the college by Pope Francis in 2023. His patriarchate has been defined by the war, during which he offered to trade himself in exchange for hostages held by Hamas. The granular details of his theology are unclear. His Italian heritage could be a benefit, counter-balancing the novelty of his candidacy with the stability of an Italian papacy.

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Countless other cardinals are floated by Vatican experts and Catholic media. Each candidate’s likelihood can bring intense disagreement over odds.

This palace intrigue is a defining aspect of the Vatican, one of the last absolute monarchies in the world and perhaps the last institution on earth where secular democracy gives way to the politics of a royal court.

The Catholic Church believes that the Holy Spirit offers itself to the cardinals for guidance in casting their ballot. It’s up to each prince of the church to decide if he’s willing to listen.