Montgomery County Executive Isiah Leggett on Tuesday proposed a slight cut in the school construction fund over the next six years — the first decrease in recent memory.

At a news conference steps from his Rockville office, Leggett (D) announced his proposal to spend $4.21 billion in capital funding over the next six years. Overall, the proposal would be $168 million more than the previous capital spending plan, which was proposed two years ago.

But Leggett proposed $1.36 billion in school construction funds, a 0.3 percent decrease from the previous plan. The Board of Education had requested $1.49 billion, or a nearly 10 percent increase.

The announcement comes as county public schools see record-high enrollment growth. About 146,500 students attend, and recent projections estimate that the enrollment total will increase by about 9,000 in five years.

Meanwhile, state officials are aggressively pushing for more school construction. Gov. Martin O’Malley (D) announced this month that in his proposed budget, which is to be released Wednesday morning, he plans to allocate more than $350 million in school construction funding, the second highest amount in state history.

It is unclear what impact a significant increase in state construction aid would have on Montgomery’s proposed capital plan.

Council staff could not recall precisely when a county executive last proposed a drop in school construction funding but said it was no more recently than the early 1990s.

Leggett said that education is the county’s top priority but that the school board’s request was too high. “You have to consider that in relationship to the overall budget and everyone else,” he said. “If they had been treated the same as everyone else, they could have gotten a reduction of 7 or 8 percent, which would have been a huge change.”

Leggett added that Montgomery College is receiving a $8 million increase — partly because of construction on its Rockville campus.

As for the public schools, he is proposing seven school additions and the construction of two new elementary schools and a new middle school. But he is delaying the modernization of most middle schools and all high schools. He has also rejected a proposed new bus depot for the school system.

Board of Education President Shirley Brandman (At Large) said she understands that the county is in a tough fiscal situation.

“It’s a very difficult balancing act,” she said. “But I have concerns about any delays.”

The Montgomery County Council must approve a capital spending plan by June 1. It is likely to hammer out most of the details before mid-March, when Leggett announces his proposed operating budget for fiscal 2013.

Although the schools would take a hit under the proposed capital plan, other departments would get significant increases. For instance, Leggett has recommended that the Department of Health and Human Services receive $59.4 million — more than triple the amount that it got in the last capital plan. The increase would help finance the construction of a new health center on Dennis Avenue in Silver Spring and a new children’s resource center.

Other new construction projects include a transit center for Montgomery Mall in Bethesda, a replacement for the 2nd District police station and long-awaited improvements to three roads in the Clarksburg area.