Keeler turned 76 in March, a year past the normal retirement age for bishops.
O'Brien, a 68-year-old New York native, served as an auxiliary bishop in New York before taking over the Archdiocese for the Military Services in Washington in 1997. He coordinated a major evaluation of U.S. seminaries in 2005-2006, ordered by the Vatican in response to the clergy sex abuse scandal.
Keeler, a native of San Antonio, was appointed archbishop in Baltimore in 1989 and marked his 50th anniversary in the priesthood in 2005. He submitted his resignation last year to the Vatican when he turned 75, as required by the church.
In May, Keeler said he planned to remain in Baltimore as head of the Basilica Historic Trust after his successor was named. He oversaw the restoration of the historic church.
The Archdiocese of Baltimore serves 510,000 Catholics in Baltimore and nine counties in central and western Maryland, according to the archdiocese Web site.
The Archdiocese for the Military Services serves about 1.5 million Catholics, including all in the military and their families.
Güncelleme Tarihi: 12 Temmuz 2007, 16:55