ROME—The Vatican is beginning the elaborate sequence of events for mourning, burying and replacing Pope Francis .

On Monday evening, some 12 hours after the pope died , the Vatican’s camerlengo, or chamberlain, is due to ceremonially certify the pontiff’s passing . By tradition, the camerlengo, American Cardinal Kevin Farrell, will call out the late pope’s baptismal name, Jorge Mario, three times. On receiving no response, he will declare that the Holy See is vacant.

Cardinal Farrell will then break the Fisherman’s Ring, the deceased pope’s signet ring, and inform the Dean of the College of Cardinals, who will summon cardinals from around the world for a conclave.

The pope’s mortal remains will then be placed in a simple wooden coffin lined with zinc. Francis last year abolished the more elaborate tradition of placing the papal coffin inside a second, then a third casket. He also scrapped the custom of displaying the pope’s body on an elevated platform in St. Peter’s Basilica—instead, he will lie in the open coffin—as well as some of the pomp and circumstance of the funeral.

The faithful will likely be able to view the pope’s body in the open coffin in St. Peter’s from Wednesday morning onward, the Vatican said on Monday, although a final decision on the arrangements is expected on Tuesday.

The funeral is expected to take place between four and six days after the pope’s death. A total of nine days of mourning are foreseen, marked by Masses at St. Peter’s and around Rome.

Francis’ simplification of his own burial is meant to convey that a pope’s funeral “is that of a shepherd and disciple of Christ and not of a powerful man of this world,” the master of papal liturgical ceremonies, Archbishop Diego Ravelli, said when the new rites were published last November.

In another break with tradition, Francis asked to be buried outside the Vatican at the Basilica of St. Mary Major, a church in Rome where he often went to pray.

Meanwhile, the cardinals from around the world will be gathering. Their first official meetings, known as the General Congregations, aren’t as famous as the conclave in the Sistine Chapel, where the election of the next pope takes place. But they can be just as crucial in determining the outcome.

The speeches and discussions, held in the New Synod Hall, a modern auditorium, are where influential cardinals will try to shape their colleagues’ sense of the priorities for the next pontificate.

“The whole mystery of the conclave is the agenda. What kind of agenda is set by the initial conversations? Then you think about the candidates,” said church historian Massimo Faggioli of Villanova University, Pennsylvania.

The homilies at the funeral Mass and on the morning of the conclave can also set the tone, said Faggioli.

Intense lobbying and networking will also be under way in informal get-togethers. There are 252 cardinals, but only 135 of them can vote. To be eligible to vote, a cardinal must be younger than 80 on the day the pope dies.

Although the older cardinals can’t vote, they can take part in the pre-conclave discussions and try to influence the agenda and mobilize support for their preferred contenders, until the conclave begins and the cardinal-electors enter seclusion.

The conclave is supposed to begin between 15 and 20 days after Francis’ death. To begin it, the cardinal-electors, who will have already taken an oath of secrecy, attend Mass in St. Peter’s, then proceed to the Sistine Chapel to start the voting.

One of the unusual features of this conclave is that the number of voting cardinals exceeds the maximum of 120 set out in the Vatican’s constitution. Francis, never a stickler for protocol, appointed numerous cardinals in far-flung countries outside the Catholic Church’s heartlands.

Thanks to this geographical dispersion, another novelty will be how few of the cardinals have previously met and gotten to know each other. It makes the days of agenda-setting, coalition-building and voting even harder than usual to predict.

Most modern conclaves have been short: Two, three or at most five days have been needed to find a two-thirds majority for a winning candidate.

Write to Marcus Walker at [email protected]