Gov. Wolf, in a stunning move, is stripping Bill Green of his chairmanship of the School Reform Commission.
Marjorie Neff will be the new chairwoman of the five-member governing body of the Philadelphia School District. Wolf will announce the move on Monday.
Green will fight the move in court.
A spokesman for the governor confirmed the move on Sunday night, and said Wolf was "well within his rights" to choose an SRC chair.
The move comes less than two weeks after a controversial SRC vote to approve five new charter schools. Citing district finances, Wolf had ordered Green to approve no new charters. Harrisburg Republicans had wanted up to 27 charters approved.
Both sides threatened consequences if their orders were not followed.
Green, in a statement, said he believed Wolf lacked the legal authority to remove him as chair. He will file a suit in Commonwealth Court, he said, but in the interim will "show up for work and do my job," and not block Neff.
State law, Green said, holds that no SRC member can be removed from office except for misfeasance and malfeasance.
"I hold the office of chair and the office of commissioner; there is no vacancy in the chair and no legal basis for another commissioner to be named chair," he said. "This is important: by limiting removal to cause, the SRC statute makes clear that commissioners, once appointed, need to be free from political repurcussions for their actions in office."
Green was named to the SRC by Gov. Corbett in 2014. Neff, a retired Philadelphia School District principal, is a mayoral pick, but the governor chooses the SRC chair.
Neff did not cast a single vote to approve any new charters.
Green said that Neff told him that she believed he was doing an excellent job, but the governor's people told her Wolf couldn't work with Green as chair.
The move could throw the commission into turmoil. Though there was some dissention on the recent charter votes, the SRC - which also includes gubernatorial picks Feather Houstoun and Farah Jimenez and mayoral pick Sylvia Simms - had worked well and usually voted together.
But the governor's move is likely to create tension and could split the SRC, which will soon introduce a budget for the 2015-16 school year. The district already faces an $80 million deficit, and will be lobbying hard in Harrisburg and City Hall for more funds.
Green also said he worried about what message the move would send to the PFT, which also opposed the approval of any new charters.
"I believe the PFT needs to allow its members to contribute to their health care like most other teachers and most Americans," Green said. "I will continue to put the interests of students first and push the PFT to contribute its fair share of solving the problems we have."
Green said he had "tremendous respect for Commissioner Neff and her years of service to the district, and I appreciate her dedication and insight as a fellow commissioner."
He said he would "continue to try to work with and help the Governor in my role as commissioner."
In a statement, education advocate and council at-large candidate Helen Gym gave the appointment her full endorsement.
"She has developed and managed some of the best schools in Philadelphia," Gym said. "Her appointment as chairwoman marks the first time a longtime educator will serve as chair of the SRC, and will provide an important shift in approach toward an invested and stable Philadelphia school system."