Citing serious concerns over Superintendent Natalie Thomas' "leadership, trustworthiness, and lack of transparency," the Cheltenham school board said Monday it plans to hire a former school chief to "monitor" her activities.

The possibly unprecedented move would be a serious blow to the tenure of Thomas, who since arriving 18 months ago has clashed with the teachers' union and administrators over numerous staff changes and departures.

Under a resolution expected to be adopted at Tuesday night's school board meeting, effective immediately former Superintendent William Kiefer would be hired as a "superintendent monitor" to investigate and assess Thomas' performance and "determine the degree to which board policies are being met under Dr. Thomas' leadership."

Kiefer, who retired in 2010 after four years as superintendent, said in an interview that he was asked to assist with "an assessment of the work environment and leadership" of the district, but declined to provide any details because he had not been formally hired.

As for the idea of hiring a former superintendent to monitor a sitting one, he said, "I think it's unique to this situation."

Marc Lieberson, a former school board member who was among 25 people to sign an October letter to the board strongly criticizing Thomas, praised Kiefer as a "no-nonsense man. He can get things fixed but at the same time maintain the morale."

He also said he never heard of a district's taking this kind of action and called it "innovative."

"I'm sorry it went this far," said Lieberson, who worked with Kiefer when he was board director. "Something's got to give, because it's not getting any better, apparently."

After retiring as superintendent, Kiefer - a retired two-star general in the Army Reserve - two years later was hired as an interim principal at Myers Elementary School when its principal, Andrew Kuhn, was promoted to principal of the high school.

Thomas' reassignment of Kuhn in July to a temporary research position, seen by many as a way to shove him out the door, and his quick departure to another district touched off a chorus of criticism of the superintendent, who is paid a salary of $180,000.

Thomas, 57, and school board President Napoleon Nelson did not return calls for comment.

The resolution cites a number of disputes and problems since Thomas arrived from Missouri in June 2013, including the October letter signed by 25 residents, former teachers, school board members, and PTO presidents that warned of a "failure of leadership" that had already caused several teachers and administrators to leave the district.

It noted a number of labor relations issues and a federal unfair labor practice suit "that are arguably attributable to the actions of Dr. Thomas."

"Because of what has become a disruptive and toxic environment for community, faculty, and students, the district believes that it has lost focus ...," the resolution said.

It also said the board believes it is "overly focused" on employee issues and mistrust rather than student performance.

Last month, Thomas scheduled several community meetings in response to complaints. The board decided that a "systematic and rigorous assessment" of Thomas' performance was needed and decided to hire Kiefer. His salary was not disclosed in the resolution.

The board noted Kiefer's abilities as a superintendent, his knowledge of the district, and the respect he has from the faculty and administration.

In addition to monitoring Thomas, the board said it wants Kiefer to work with her to restore calm and stability "to a district that is no longer calm and is arguably unstable at this point."