世界各国政要出席教宗方济的即位弥撒

The Vatican is prepared for a huge crowd Tuesday as Pope Francis hosts political leaders from 130 nations and representatives from a variety of religions for his installation Mass.

Hundreds of thousands of people are expected to pack St. Peter's Square for the celebration, which formally installs Francis as the new leader of the world's 1.2 billion Roman Catholics.

Among the high-level guests, the spiritual leader of the world's Orthodox Christians, Bartholomew, is expected to attend.  He would be the first patriarch from the Istanbul-based church to witness a papal inauguration since the two branches of Christianity split nearly 1,000 years ago.

More than 30 delegations of other Christian churches, as well as representatives from the Jewish, Muslim and various other faiths, also will attend.

Argentine President Cristina Fernandez de Kirchner arrived prior to Tuesday, in order to meet with the new pope, who hails from her country.  U.S. Vice President Joe Biden, a Catholic, also is one of the political leaders in attendance.