Maryland education officials signaled today their willingness to follow through on a long-standing threat to seize control of the state's most troubled public schools that fail to improve test scores--possibly as early as next spring.

In a unanimous vote, the state Board of Education decided to seek bids from private firms to run such schools.

If the board hires a company, it would mark the first time a state government in the country had detached an individual school from local control. Although the first school--or schools--taken over would almost certainly be from the beleaguered Baltimore system, the move also serves as a warning to Prince George's County, where the state has put 12 schools on a probation-like status over the past two years.

State officials acknowledged that such a takeover move, which was immediately denounced by the state teachers union, was bound to stir up political strife within the city of Baltimore but said they did not believe they could wait much longer.

"We have an obligation to the children in those schools," said State Superintendent of Schools Nancy S. Grasmick. "We can't tell them, 'Let's give [them] another three years.' "

Yet Grasmick, who has faced criticism in some quarters for not intervening in the schools sooner, declined to commit her agency to taking over a school this year, describing today's move as a serious but "exploratory" step.

And board members expressed some discomfort with the prospect of taking control of schools, indicating they may choose to investigate other options, such as closing the schools.

Since 1993, when the takeover threat first sent tremors through the ranks of the state's teachers and principals, nearly 100 schools--most in Baltimore--have been placed on the dreaded "reconstitution-eligible" list.

Many of those schools have shown little or no improvement on Maryland's skills-testing standardized exams. Some critics have complained that students were being left to flounder in failing schools while the state hesitated to take the political and logistically complex next step, and that local school officials no longer took the threat seriously.

Grasmick and other state officials have responded that it takes time to turn around a school and that the Baltimore schools were ill-equipped to deal with their own problems until the state forced an overhaul of the city system two years ago. Still, state officials had until now offered little in the way of guidelines or deadlines for determining when to give up on a school or how to proceed with a takeover.

State Department of Education officials said they will scrutinize the latest test scores of the first 42 schools that were named to their list three to five years ago. Any whose low scores are stagnating or dropping will be considered for takeover, Grasmick said.

Two of the schools on the list are from outside Baltimore, but both of them--Van Bokkelen Elementary in Anne Arundel County and Woodson Middle in Somerset County--have shown improvement in recent years, Grasmick said, and probably are not at risk.

Eight firms and nonprofit foundations have already indicated they may submit bids. Any firm that is selected would receive the same amount of local and state funding directed to that school previously. State officials have not determined whether the contractors would be free to hire and fire school staff as they please.

Patricia Foerster, vice president of the Maryland State Teachers Association, said union officials oppose any school takeover. "If we can find the resources to pay a management group, why can't we support the system in the first place?" she asked.

But Prince George's School Superintendent Iris T. Metts said she was not necessarily opposed to such action: "Sometimes outsiders can change the climate of a school faster, and that's the most important thing--changing the climate to help make a turnaround."

Metts said the county is working hard to get its schools off the state's list, "but I'm not interested in who has control. It's what's good for the children."

James McPartland, director of Johns Hopkins University's Center for Research on the Education of Students Placed at Risk, which has worked closely with one of Baltimore's targeted high schools, said the state should pick a contractor with school reform credentials.

"Just trying harder doing the same old thing with newer people won't work," he said. "We need to comprehensively overhaul our urban schools."