DURING HIS successful campaign for New York mayor, Bill de Blasio (D) made clear that he had a different, less favorable view of public charter schools than did his predecessor. But even charter advocates who feared the worst wouldn’t have predicted that Mr. de Blasio would kick a high-achieving charter school out of its building, leaving hundreds of parents wondering where their children will attend classes next fall.

Success Academy Harlem 4, whose students boast some of the highest math scores in New York state, faces an uncertain fate in light of Mr. de Blasio’s decision to deny it free space. The school, in operation since 2008, is part of the Success Academy chain, which serves minority and low-income children with impressive results. The chain’s chief executive, Eva Moskowitz, is a political rival of the mayor; during the campaign, he said of her: “She has to stop being tolerated, enabled, supported.” Mr. de Blasio also rescinded the co-locations of two planned Success schools that had been approved by former mayor Michael Bloomberg.

The de Blasio administration has pushed back on suggestions that its decisions were politically motivated. Officials complain that decisions about school space were rushed by the Bloomberg administration so as to tie their hands; they say that the majority of co-locations, in which charters share space with traditional schools, were approved, including five other proposals from Success Academy. That is small consolation to such parents as Maria Rodriguez, who told us that she is beside herself with worry over where her three children will go if Success Academy has to shut its doors.“This is the future of my children they are playing games with,” she said, dismissing the nearby failing traditional schools as an option.

The city’s indifference to the success of this school (shouldn’t performance be a factor in who gets space?) is, unfortunately, emblematic of Mr. de Blasio’s stance toward charters. His newly revised capital budget shifts $210 million from charter schools to boost other programs. Charter schools serve about 6 percent of the New York City student population. Mr. de Blasio is correct in saying they aren’t the silver bullet to fixing public education, but they play an important role, and it’s illogical to deny them the support merited by their importance to poor and traditionally neglected students.