Bishops to open 3-week synod

VATICAN CITY -- Bishops from around the world begin tackling major issues facing the Roman Catholic Church today, including whether Communion should be given to Catholic politicians who back abortion rights and to the divorced who remarry without getting an annulment.

The priest shortage and whether celibacy contributes to it, as well as dwindling Mass attendance, are also expected to be discussed at the three-week Synod of Bishops, during which bishops will offer recommendations to Pope Benedict XVI.

The Vatican said yesterday that 256 bishops from 118 countries will participate, the most ever.

Archbishop Sean P. O'Malley of Boston will not be at the gathering. His spokesman, Terrence C. Donilon, said that because O'Malley would not be serving on a committee for this synod, ''he felt it better he spend his time attending to issues here."

Benedict formally opens the synod with a Sunday Mass, and in many ways the meeting is as much about him as it is about the bishops, since it is the pontiff's first major Vatican undertaking since he was elected April 19.

Many participants have cited the changes Benedict made in organizing the synod as evidence that he wants it to be a more collegial exchange of ideas, rather than a meeting with a preordained outcome. Bishops will speak for six minutes rather than eight, allowing for an hour of open discussion at the end of each day.

''That in itself, while subtle, is a real emphasis," said Bishop Donald Wuerl of Pittsburgh, one of the American delegates attending the Oct. 2-23 meeting

Michael Paulson of the Globe staff contributed to this report.