On March 17, 19 parents who send their children to Success Academy, a Harlem charter school, filed suit in federal court to stop New York Mayor Bill de Blasio from denying them previously arranged space in a public school building. Without space, their children and 173 others will not be able to continue at Success Academy this fall.

School bullying is a problem nationwide, but in New York the bullies are de Blasio and his pals — state NAACP President Hazel Dukes and teachers unions. Their targets are middle-school kids, 97 percent of them minorities, and 80 percent eligible for lunch assistance.

Overcoming disadvantages, these middle-schoolers have soared to the top 1 percent citywide in overall student achievement. The fifth-graders rank first in New York State in math — surpassing students in Bronxville, Scarsdale and other wealthy New York suburban school districts, where resources are available at school and at home.

So why try to force the closing of this successful school? De Blasio, who sounds like a communist, is outraged that charter schools receive donations from “very wealthy Wall Street folks.” The parents’ legal complaint documents show how de Blasio targeted their school during his mayoral campaign last fall, vowing to make the school pay rent, something other public schools don’t have to do.

De Blasio’s fellow bully Dukes blasted the lawsuit on Monday. She called the suit “an outrageous and insulting attempt by Wall Street hedge fund managers to hijack the language of civil rights in their shameless political attack on Bill de Blasio.”

Sadly, it is Duke who is playing the race card for political gain and sacrificing minority children.

Consider what another Success Academy called Bronx 2 is doing to educate minority students. In that charter school, 97 percent of students passed state exams in mathematics, and 77 percent passed English. In math, the school ranks third in the state, besting schools in well-heeled suburbs. Bronx 2 shares space with a district public school, where kids under the thumb of the union and city bureaucrats, are failing. Only 3 percent passed the state English test. Same building, but a world of difference. Which school is giving kids their civil rights? Not the one Dukes and de Blasio are defending.

This is not just a local scuffle. Across the nation, teachers unions and civil rights opportunists are planting themselves on schoolhouse steps, determined to stop school choice and the emergence of charter schools that serve minority kids rather than union bosses.

Despite this opposition, charter schools are blossoming. In the 2013-14 school year, nearly 300,000 more students enrolled, 600 more charter schools opened, and total enrollment increased by 13 percent. Still, nationwide enrollment is only about 2.5 million students. But in certain cities — New Orleans, Detroit and Washington, D.C. — charter schools are burgeoning and provoking opposition.

Not from parents, but from socialist ideologues and union bosses. In New Orleans, where Hurricane Katrina uprooted the district school system, school choice has virtually replaced it. Now, roughly 90 percent of public school students attend charters. But that’s only part of the story. Nearly one-third of the city’s students attend private schools, often paid for through vouchers, their parents choose for them.

Early results reported by Tulane University’s Cowen Institute for Public Education Initiatives suggest school choice is working. More students are graduating from high school prepared for college or work.

Get ready for the bullies. U.S. Attorney General Eric Holder sued to stop school choice in New Orleans, arguing that it was getting in the way of the federal government’s 1975 court-ordered desegregation plan. When parents protested that they wanted to be the ones choosing their kids’ schools, not the Department of Justice, Holder’s lawyers told the court that parents lacked the standing to make their views known.

If anyone has standing in their child’s education, it’s parents. And parents in New Orleans said that racial balance was less important to them than being able to choose a school that educates their child. Ultimately, Holder had to give up.

Bullies often do, when you stand up to them. That’s what the parents at Success Academy are doing in the lawsuit filed Monday.

Betsy McCaughey is a former lieutenant governor of New York and the author of “Beating Obamacare.”