Cardinals during their first meeting Monday 3/4/2013, a precursor to setting a date for the official conclave to replace retired Pope Benedict. Photo credit: OSSERVATORE ROMANO

VATICAN CITY - Let the voting begin. The 115 Catholic cardinals tasked with choosing the ancient Roman church's new leader walked Tuesday into one of the world's most iconic chapels for the first day of the papal conclave -- the ritualistic voting process that will see them elect the next supreme pontiff.

After each man swears an oath on the bible, all non-cardinal electors will be asked to leave, the doors will be closed behind them, and the entire election will take place completely in secret.

There is no deadline for the cardinals to elect a new pope -- the process will take as many days as necessary to achieve an absolute majority winner; 77 of the 115 cardinal electors must agree on one man to lead them for the indeterminable future. The world will know that the 266th pope has been elected only when white smoke appears over the Sistine Chapel and a Vatican bell chimes.

Tuesday morning, the so-called "princes of the Catholic Church" began with a pre-conclave Pro Eligendo Pontificate Mass in St. Peter's Basilica at the Vatican.

Torrential downpours in St. Peter's Square kept the number of faithful and curious low as inside the Basilica, Angelo Sodano, dean of the College of Cardinals, asked his fellow cardinals "to cooperate with the Successor of Peter, the visible foundation of such an ecclesial unity."

Sodano's appeal for unity came 12 days after the first resignation of a pope in almost 600 years, and hinted at the daunting task facing the new Catholic leader: to steer the Church carefully out of an era marked by scandal and allegations of infighting and mismanagement.

Pope Benedict XVI's resignation exacerbated the problems the Church has been attempting to deal with quietly for more than a year. It sparked speculation that the theft and publication of private documents from the pontiff's own desk, which revealed the level of corruption and poor business practice in the Vatican government, might even have catalyzed his decision to step down.

In his wake, the now-Pope Emeritus Benedict left a Church divided, by many accounts, between the Vatican's inner-circle of prelates who dominate its bureaucracy, known as the Curia, and cardinals from outside that circle who feel, perhaps more keenly, pressure from their congregations and the world at large to drag the 2,000 year old institution into the 21st century.

Cardinals from the Americas, Asia and Africa have indicated that it is time for change, throwing around words like "transparency" and "openness" which may make some of their colleagues in the Church who cherish its long-entrenched tradition of secrecy uncomfortable.

The cardinal electors -- by Church rules all cardinals under the age of 80 who are physically able to attend -- have already spent a week discussing amongst themselves the qualities the new pontiff should possess, and whom among them they believe is best suited to the task.