VATICAN CITY — Pope Francis' diplomatic skills will be put to the test on today as he hosts political leaders from 130 nations and religious representatives from a variety of faiths who are descending on Rome for his installation Mass, with Latin America strongly represented to celebrate the first pope from the New World.

Among the VIPs expected is the spiritual leader of the world's Orthodox Christians, Bartholomew I, who will become the first patriarch from the Istanbul-based church to attend a papal investiture since the two branches of Christianity split nearly 1,000 years ago. His presence underscores the broad hopes for ecumenical and interfaith dialogue in this new papacy given Francis' namesake, St. Francis of Assisi, and his own history.

Francis' diplomatic mettle was tried on Monday as he held his first audience with a visiting head of state, having lunch with his political nemesis, Argentine President Cristina Fernandez, who asked him to intervene in the dispute with Britain over the Falkland Islands.

It was a baptism by fire, given that the former Archbishop of Buenos Aires has been on record as saying Britain "usurped" the remote islands from Argentina and last year paid homage to the Argentines who were killed trying "to reclaim what is theirs for the fatherland."

Argentina and Britain fought a 1982 war over the islands, which Argentina calls Malvinas. Earlier this month, the islanders voted overwhelmingly to remain a British Overseas Territory.

There was no indication that Francis, now pope, would take up the request from Fernandez, with whom he has clashed for years over her populist policies on gay marriage and other hot-button issues like birth control that will soon confront Francis on a global scale as leader of the world's 1.2-billion Catholics.

Francis may well map out some of his own priorities in his installation Mass on today, which aside from 132 official delegations is expected to draw scores of Jewish, Orthodox and other Christian representatives.