Joshua P. Starr, superintendent of Montgomery County Public Schools, speaks with Walt Whitman High School administrators in 2013. (Maddie Meyer/The Washington Post)

Montgomery County Schools Superintendent Joshua P. Starr will step down in two weeks, abruptly ending his tenure after failing to convince a majority of the school board that he was leading Maryland’s largest school system in the right direction.

School officials gave no immediate explanation for Starr’s departure from the 154,000-student district, where he was welcomed in 2011 as a man of infectious personality and big ideas. The eight-member school board voted unanimously Tuesday to approve an agreement with Starr that opens the way for a national search for a new superintendent.

Starr, 45, flanked by board members at a packed midday news conference, said he was proud of his work in Montgomery but accepted the agreement to part ways. It was a sudden fall for a well-known leader who has enjoyed the national limelight as a critic of what he sees as the education establishment’s overreliance on tests.

“While I am not happy certainly at the way things have turned out, at the same time, it is absolutely the board’s authority to move in a direction that they see fit,” Starr said. “I am a superintendent of schools. I hold no illusions about longevity in the job or anything else.”

Montgomery County is a consistently high-achieving district with improving graduation rates and strong SAT scores. County officials familiar with school board deliberations told The Washington Post that Starr’s exit was not the result of a single issue; instead, a series of perceived missteps added to a simmering concern about Starr’s ability to build on the success of Jerry D. Weast, who retired in 2011 after a 12-year run.

County officials, who spoke on the condition of anonymity because they were describing private conversations, said the board members who lost faith in Starr cited concerns with his approach to closing the school system’s achievement gap and his candidacy for the chancellorship of New York’s public schools after a little more than two years in Rockville. They said his personal style was at times remote and dismissive, and they mentioned the lack of coherent vision for principals at the district’s 202 schools.

One of the broader complaints about Starr has been a disconnect between his ideas and concrete action. He was praised for being more collaborative and flexible than his hard-charging predecessor. But some in Montgomery began to question how much he had accomplished and whether it justified four more years.

Board of Education President Patricia O’Neill said that the board deliberated about Starr’s future for several weeks and that both sides agreed it would be in “the best interests of the district to appoint a new leader to carry forward the board’s vision.” When pressed about reasons for Starr’s exit, O’Neill said: “There are eight individuals on the board, with eight different thoughts, opinions, using their own instincts in evaluating the system.” She acknowledged she had supported Starr. “I am only one individual.”

Montgomery County Council member Nancy Navarro, reflecting on what went wrong, recalled the “expectation that Starr would take the school system into the next level.” Navarro is a former member of the school board.

“Four years went by, and people were still waiting . . . to hear what the new direction was all about, where are we going,” she said. “That was never really articulated. Meanwhile, the system experienced a lot of challenges.”

Starr’s exit illustrates the precarious status of large-district superintendents. Many answer to local school boards whose members campaign on promises of rapid improvement or change. Expectations have risen quickly during the past decade, while at the same time, many localities have cut public school funding.

In Montgomery, with an enrollment surge and budget strains, Starr’s three-year, seven-month tenure was slightly above the national average of 3.2 years for large-district superintendents, according to a 2014 study by the Council of the Great City Schools. School systems in the Washington area have had significant turnover in the past two years, with new superintendents in Fairfax, Loudoun and Prince George’s counties; the District’s chancellor is in her fourth year.

“It’s a much more difficult job today than it was even 10 years ago,” said James Harvey, executive director of the National Superintendents Roundtable, a coalition of superintendents. “The demand is for superintendents to produce superior results for all students at a time when the intake for schools is much more challenging.”

Starr is scheduled to leave his $264,000-a-year post on Feb. 16. Larry A. Bowers, the school system’s chief operating officer, will serve as interim superintendent through June 30. Board members hope to have a permanent successor in place by July 1.

Under the terms of a separation agreement, Starr will be paid until his contract ends — a sum of about $100,000 through June 30 — and will receive health insurance through the end of 2015. He is also entitled to more than $46,000 in unused sick, vacation and personal leave. The agreement stipulates that Starr and board members “refrain from making disparaging remarks regarding the other.”

Starr’s tenure had its rocky moments, which included the revelation that a majority of the 30,000 high school students in the high-performing district failed final exams in key math courses in 2013, a problem that stumped school officials and led to a five-point plan.

The district also was criticized for its handling of allegations of sexual abuses at county schools, and Starr took heat from parents after he recommended shelving an effort to change high school bell times. The school board rejected Starr’s recommendation and asked him to come up with lower-cost options.

County Executive Isiah Leggett (D), who privately lobbied board members to reconsider their opposition to Starr, expressed regret.

“I’m disappointed,” he said. “I’d hoped he would be able to stay. But it’s the decision for the board to make, and they had their own rationale. That’s unfortunate. He was a positive asset in my opinion.”

Starr said Tuesday that he has often called the role in Montgomery one of the best jobs in public education. “Even today, I still feel that way,” he said.

Looking back, Starr said he doesn’t think he made any major mistakes. “We have a record of accomplishments; we’ve got results,” he said.

Starr detailed his record in a recent memo to the board, citing improvements in SAT scores and graduation rates, including for minorities, and a narrowing of the achievement gap.

Starr’s political troubles with the board left many wondering how well he cultivated those relationships — and how well board members communicated their wishes. He needed five votes on the board to get a new contract; the county officials familiar with the board’s decision said four members were entrenched against Starr staying.

Starr arrived in Montgomery in July 2011, a bookish New Yorker who started his career as a substitute English teacher in Brooklyn. He’d never been a principal, and after he had held a series of administrative posts in New York and New Jersey, his first superintendency was of the 15,000-student Stamford Public Schools in Connecticut.

At the time, O’Neill said the board was taken by Starr’s “enthusiasm, his research of us, his commitment to data-driven decision-making and his youth.”

Emma Brown contributed to this report.