AUGUSTA, Maine — Maine Corrections Commissioner Joseph Ponte, who has been credited with initiating improvements in Maine’s prison system, has been hired to run the jails of New York City.

A press spokeswoman for New York City Mayor Bill de Blasio confirmed the appointment early Tuesday afternoon. Ponte will succeed Mark Cranston, who has been acting commissioner since March 2013.

Ponte, who has been commissioner of Maine’s Corrections Department for three years, received praise from prisoner advocates for reducing the number of prisoners in segregation.

“We think New York City is making a wise choice,” Rachel Healy, the communications director for the American Civil Liberties Union of Maine, said Tuesday afternoon. “Commissioner Ponte has been instrumental in making smart reforms within the Maine correctional system, including reducing our reliance on solitary confinement. We hope he’ll work with advocates in New York City to continue the good reforms that we’re starting to see there.”

Ponte will be charged with overhauling the city’s corrections system by ending the overuse of solitary confinement, curtailing officers’ use of excessive force and improving resources to handle the mentally ill, a news release from the mayor’s office stated.

“In his 40-year corrections career, Joseph Ponte has earned a national reputation as a successful reformer,” a release from the mayor’s office states. “Ponte has a broad range of experience that offers a unique perspective and deep understanding of corrections system management. Ponte has served as a correctional officer, a warden, and as director and commissioner of numerous corrections systems around the country, and understands the challenges each member of the corrections community faces. As commissioner of the Maine DOC, Ponte instituted reforms that reduced the use of solitary confinement by two-thirds, and completely eliminated the use of disciplinary segregation for people identified as mentally ill.”

In New York City, on an average day in 2013, there were 11,827 inmates incarcerated in the city’s 10 jails, four borough houses of detention, court pens and two hospital wards, according to the New York City Department of Corrections. By contrast, just 2,194 Maine inmates were confined at the beginning of March in all of the state’s prison facilities.

Republican Gov. Paul LePage, who in 2011 chose Ponte to run Maine’s corrections system, thanked and praised him Tuesday.

“Commissioner Ponte has done an excellent job for the state of Maine,” said LePage in a prepared statement. “He will be difficult to replace, but we wish him well in his new position.”

Steve Lewicki, the coordinator of the Maine Prisoner Advocacy Coalition, said that although the advocacy group and the commissioner didn’t always see eye-to-eye, Ponte “maintained a dialogue with us that is unprecedented in this state.”

“We’re going to miss him, because he was progressive. This department of corrections needed a mix-up, and he did that when he came here,” said Lewicki, who was incarcerated in Maine for 15 years before his release two years ago. “We didn’t agree with all of his changes, but many of them did make the prison a safer place.”

Neither a new Maine Department of Corrections commissioner nor an acting Department of Corrections commissioner has been announced, according to the state Corrections Department.

Lewicki and other prison reform advocates said Tuesday that they hope that Maine’s next commissioner will continue to have open lines of communication with them. They also hope the next commissioner will continue programs that have been initiated or expanded under Ponte’s watch, including the volunteer hospice program at Maine State Prison, and will continue to make reforms that might include ceasing the practice of double-bunking inmates in a high-security unit at Maine State Prison.

The Rev. Stan Moody, a prison reform activist who formerly served as the Maine State Prison chaplain, said that he has worked with Ponte a lot. He found the commissioner’s reputation as a fixer of troubled corrections systems is well-deserved — but wished nonetheless that Ponte had stayed in Maine longer.

“I think he’s had a very tough job, and under the circumstances, has done a lot of good things,” Moody said. “However, he hasn’t had long enough in this period of time to gain the trust of people on the inside. The jury is still out to see if the changes he’s made will stick.”