The 61-year-old Aquila, currently bishop of Fargo, N.D, studied at Denver's St. Thomas Seminary and worked in several Colorado parishes after his ordination in 1976.
Chaput built a reputation in Denver as a conservative leader, devoted to evangelism and outspoken about his disapproval of "cafeteria Catholics" and Catholic politicians who support abortion rights.
Aquila has been outspoken in his previous post, telling a radio interviewer in December that groups like the American Civil Liberties Union are endangering the nation's future by "the removal God from anything."
The Denver Archdiocese has scheduled a news conference for Monday morning.
(Copyright 2012 by The Associated Press. All Rights Reserved.)