Alexandria Superintendent Morton Sherman is leaving the city’s top schools job immediately, putting the district’s leadership in limbo just days before the start of the school year.

The Alexandria School Board voted 8 to 1 Thursday night to release Sherman, who was hired in 2008, from his contract. The surprise move negated the final 22 months of his current three-year agreement, which was set to expire in June 2015.

The board appointed Margaret May Walsh, the school system's chief policy and student services officer, as acting superintendent. The city will launch ­searches for an interim superintendent and a new permanent schools leader.

In an e-mail sent to staff members and supporters on Thursday, Sherman thanked them and called his five years leading the Alexandria public school system “among the most rewarding and emotional I have ever experienced.”

“For personal and professional reasons, it’s time for me to move on,” Sherman wrote. He said he intends to pursue volunteer work and spend more time with his family.

Sherman did not return requests for comment Thursday.

Sherman’s departure came suddenly, as the school system is preparing to open its doors to 13,500 students for the school year that begins Tuesday. Several outside observers said the move comes after months of increased tension and personality conflicts between the superintendent and a new, more hands-on school board. Seven of the nine board members took office in January.

Marc Williams, one of the returning members, was the lone dissenting vote on Thursday.

“This is not a sound way to make a transition,” Williams said.

In 2012, Sherman came under fire because of serious mismanagement of the capital improvements budge t, which led then-Vice Mayor Kerry Donley (D) to call for his resignation . Soon after, state investigators found testing irregularities in the city’s adult education program.

More recently, there has been increased scrutiny of the school system’s performance.

New board members were sworn in just before the Jefferson-Houston school in Old Town became one of the schools in Virginia targeted for a state takeover because of chronic low performance.

“We have a difficult situation coming up if we don’t make some extreme improvements. I think the School Board has seen that fact,” said City Council member John Chapman (D), who took office in January.

School Board Chairwoman Karen A. Graf said in a statement that the board “decided to release Dr. Sherman from his remaining contract after a great deal of deliberation.” The board agreed to pay Sherman $281,507 in salary and paid leave in response to his “request to arrange for an early retirement,” according to a board statement. The compensation covers 39 percent of his remaining contract months.

Sherman asked earlier this summer to be released from his contract, Graf said. It took until now to complete the negotiations, and board members thought that a midyear transition would be more difficult.

“We thought it would be good to have a fresh start at the beginning of the school year,” Graf said in an interview Thursday. “This is not how we pictured this year going, and we want to commend our staff for stepping up and going forward.”

Also in a statement released by the School Board, Sherman said he is confident that the board, school staff and the community will continue to work together to move the school district forward.

“Alexandria is a wonderful community and I have thoroughly enjoyed my time at ACPS,” Sherman said in the board’s statement. “It has been my pleasure to serve these amazing students and to work with these dedicated educators.”

Some parents questioned the timing of Sherman’s departure when they heard about it Thursday.

“I’m worried we will feel somewhat rudderless as we begin a new school year,” said Marianne Hetzer, the parent of a senior at T.C. Williams High School, a school many in the community think has turned around in recent years.

In Sherman’s letter to staff members, he listed some of his accomplishments, including the creation of a K-12 curriculum, reforms at T.C. Williams, the expansion of preschool, a reduction in elementary class sizes and the establishment of new goals to close minority achievement gaps.

Williams, the School Board member who voted against the move, lauded the superintendent for making “continuous improvement” to the system and called the reforms at T.C. Williams, which have significantly improved academic performance and graduation rates, a “crowning achievement.”

Melynda Wilcox, president of the Alexandria PTA council, said she was frustrated by the abrupt change.

“We are finally seeing some of the positive results from some of the things he brought to Alexandria,” Wilcox said.