CHICAGO (CBS) — An 80-year-old South Side Catholic pastor who was active in the Civil Rights Movement is now butting heads with his replacement, and with Francis Cardinal George.

As WBBM Newsradio’s Bernie Tafoya reports, the Rev. Dan Mallette becomes pastor emeritus of St. Margaret of Scotland Church, at 9849 S. Throop St. in the Longwood Manor neighborhood, on Sunday. At that time, his replacement, the Rev. Bill O’Donnell, will replace him as pastor.

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LISTEN: WBBM Newsradio’s Bernie Tafoya reports

Mallette has a good number of parishioners who are loyal to him, including Cook County Sheriff Tom Dart, the Chicago Sun-Times reports.

The Sun-Times says the Chicago Archdiocese wants Mallette to leave the church for the next six months, so necessary repairs can be made to the rectory, and so O’Donnell can begin making his own imprint on the parish.

O’Donnell and the Archdiocese say Mallette’s health and safety are factors.

But Mallette is not going quietly. He had some less-than-kind words for his successor, and is quoted in the Sun-Times article as calling O’Donnell “a genius at being a pain in the ass.”

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Mallette accuses the new pastor of forbidding him from saying mass in the church and cutting off his phone lines, and he accuses Cardinal George of going back on his word to allow him to stay at St. Margaret of Scotland, the Sun-Times reports.

Mallette has been a fixture at St. Margaret of Scotland since 1977. He also has a long history of working for civil rights in Chicago, and marched with Dr. Martin Luther King Jr. in Alabama.

As pastor, the Sun-Times reports, Mallette has built one of the city’s most diverse congregations with numerous worshipers both white and African-American.

But the surrounding neighborhood has been plagued for many years by gang violence, and assailants have twice attacked Mallette in his rectory bedroom.

The first time, in 2002, he fought them off, the Sun-Times reports. But last year, the robbers beat him and left him with broken ribs and facial injuries, in a brutal attack that dominated the headlines in early December.

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Since then, Mallette has returned to work, but still needs regular medical attention, the Sun-Times reports. O’Donnell is quoted as saying Mallette needs to accept his physical limitations and “let go.”