This flier, which disparages Center School Principal Elaine Schwartz, appeared on the building's fence and around the neighborhood.

A tiny middle school on the Upper West Side that has flown under the radar for much of its 26-year history has become the object of intense scrutiny in recent weeks as its principal and parents threaten to derail the neighborhood’s plans to alleviate overcrowding.

A plan proposed last week by the Community Education Council for District 3 would require the school to move from its longtime home to a larger space several blocks away. That plan, and the Department of Education’s response to it, will be the topic of a CEC 3 meeting tonight.

But Center School Principal Elaine Schwartz has opposed relocating since the DOE originally suggested the idea in September, and the school’s loyal parents have lined up behind her.

“We are totally unified,” parent Alan Madison told me. “When it comes to the education of our children, we listen to [Schwartz].”

Schwartz, the 26-year-old school’s founding principal, told the New York Times last week that she opposed a move under any circumstances.

As Schwartz and her school have dug their feet in, tension has wracked the PS 199 building on West 70 Street, where the Center School is the sole occupant of the top floor.

PS 199 parents say they can’t figure out why the Center School is so intent on staying in a too-small space, and parents zoned for PS 199 have mobilized to support CEC 3’s plan, which would guarantee their children a kindergarten seat next year.

For their part, Center School parents are lobbying just as hard to oppose the plan. They have dutifully shown up for every CEC meeting since the rezoning process began; the school’s Web site calls for “a sea of Center School parents” to sit front and center at tonight’s public CEC meeting.

The tension has at times gotten ugly: Someone posted fliers that called Schwartz a “principal/dictator” on the fence around the building. And Center School parents charge that racism and class prejudices are behind the move to evict their school, citing postings from last January on the gossipy Web site Urban Baby that called Center School students “thugs.” (PS 199, a zoned school, is two-thirds white, while the Center School, which draws its students from throughout the district, is half white and has a higher proportion of black and Hispanic students.)

Center School parents say the real issue is a pragmatic one: Because moving the Center School would free up so little space, the CEC will have to revisit the space issue within a few years. “The draft proposal for the CEC does not focus on the district-wide overcrowding,” Joanna Carlovich, the school’s PTA president, told me.

A superior solution, parents say, would be to move Anderson to the MS 44 building, which the citywide gifted school has said it would do, and then to create a new elementary school in the free space at PS 9.

But that plan, floated informally at one meeting by a DOE official, would require PS 199 to have only two kindergarten classes next year, down from seven this fall, and those would be made up wholly of siblings of currently enrolled children. Families zoned for PS 199 consider such a plan unacceptable.

It would also prevent the overcrowding at the Center School from being relieved, but parents there aren’t worried. “Our kids learn in the hallways and we’re totally fine with it,” Madison said.

Tonight’s public meeting where CEC 3 will hear comments about the plan is sure to be charged. But if the council’s proposal becomes policy, Madison warned that Center School parents might pursue “nuclear options,” including seek a legal injunction to stop the move.