A high-ranking Holy See official who tried to resolve tense relations between the Vatican and U.S nuns was transferred Thursday to a Midwestern archdiocese of fewer than 230,000 parishioners.

The newly appointed Indianapolis Archbishop Joseph Tobin said he didn't know if the move was related to his efforts to reconcile the heads of the Roman Catholic Church with nuns who some theological conservatives complained had become too secular and political.

"No one told me it was tied to the investigation," Tobin, a 60-year-old American Redemptorist priest, said at a news conference in Indianapolis. He succeeds Archbishop Daniel Buechlein who retired last year.

After his introduction at Saints Peter & Paul Cathedral in Indianapolis, Tobin said it hadn't been easy to leave his post as the No. 2 official in the Vatican office that oversees religious orders worldwide, comprising about a million men and women. He said he hadn't been looking for a transfer.

When Pope Benedict XVI appointed Tobin to his former position, in 2010, two different Vatican agencies — one of them the office where Tobin worked — were investigating American nuns' adherence to church doctrine.

Tobin tried unsuccessfully to soothe tensions by promoting dialogue between the sisters and the Vatican.

The results of the investigation by Tobin's agency have not been made public. But following the other probe, the Congregation for the Doctrine of the Faith ordered a full-scale overhaul of the National Conference of Women Religious, which represents about 80 percent of U.S. nuns, accusing it of taking positions that undermine Catholic teaching and promote radical feminist themes incompatible with the faith.

The reaction to the proposed overhaul has been intense, with priests and ordinary Catholics alike voicing support for the sisters who run schools, hospitals, shelters and other vital social services that cater to the poor.

The Rev. Thomas Reese, a senior fellow at the Woodstock Theological Center at Georgetown University, said Tobin stuck his neck out for the nuns.

"He said part of his job was to explain Women Religious to the Vatican," Reese said. "That was just unheard of because it insinuated that they (the Vatican) just really didn't get it."

The Rev. James Martin, a Jesuit priest and contributing editor to America magazine, a weekly Catholic publication, said Tobin's replacement should be someone with an equally open mind.

"I hope that his successor will also be open to listening to the experiences of the sisters," Martin said.

Tobin, a native of Detroit, was ordained in 1978. Before being named to the No. 2 position in the Vatican's office for religious orders, he was a member of the committee of international religious superiors who meet regularly with the officials from the Vatican to discuss issues of concern to religious congregations.

The Indianapolis archdiocese counts about 225,000 Catholics in its 39 counties in central and southern Indiana.