PORTLAND, Maine — The Roman Catholic Diocese of Portland has named an interim superintendent of schools to succeed its longtime school chief, who announced her retirement.

The Rev. Louis Phillips, rector of the Cathedral of the Immaculate Conception and administrator of the Portland Peninsula and Island Parishes, will become interim superintendent when Sister Rosemary Donohue retires at the end of June. The ultimate plan for Donohue’s replacement is “still to be determined,” according to a news release from the diocese.

Phillips holds a master’s degree in education administration and a doctorate in curriculum, instruction and administration from Boston College. He has served in teaching and administrative posts in schools and colleges in Maryland, New Jersey, New York and Ohio. Most recently, Phillips served as an adjunct assistant professor of education at Saint Joseph’s College of Maine in Standish.

Bishop Robert Deeley said Phillips has a “strong background in education and is eager to contribute his gifts as we assess the best ways to grow and strengthen our schools.”

Phillips has served at several parishes throughout the Maine since his arrival in 1998, including Auburn, Augusta, Ellsworth and Portland.

Donohue will step down June 30 after 21 years as superintendent in the diocese.

“Making the decision to leave at the end of this school year was difficult, but I am confident it is the right choice,” Donohue said in a written statement. “I feel that as the Diocese of Portland transitions from the leadership of one bishop to another, it is the appropriate time for me to pursue other opportunities and, more importantly, enjoy my family and community. By announcing this now, it will also give the diocese the opportunity to carefully select the next superintendent.”

The superintendent oversees 10 diocesan schools in Auburn, Augusta, Bangor, Biddeford, Brunswick, Portland, Rumford, Sanford, South Portland and Winslow.