The Chicago school system filed suit against Illinois Republican Gov. Bruce Rauner and the Illinois State Board of Education Tuesday, alleging that the way the state funds schools violates the civil rights of minority children and that the state employs “separate and unequal systems of funding for public education in Illinois.”

The lawsuit was filed in the Cook County Chancery Division by the Chicago Board of Education on behalf of five African-American and Latino Chicago Public Schools families. It comes as Chicago Mayor Rahm Emanuel’s administration has been pressing the Republican governor and state Legislature for months to change how the state distributes tax dollars to Illinois’ schools. The Chicago Tribune reports that the lawsuit asks that the state be barred from distributing state aid in “a manner that discriminates against plaintiffs.”

“The state treats CPS’s schoolchildren, who are predominantly African-American and Hispanic, as second-class children, relegated to the back of the state’s education funding school bus,” the lawsuit says.

Chicago Public Schools, which have about 380,000 students, received about 15 percent of the state’s $10.6 billion in education funding, despite enrolling nearly 20 percent of Illinois’ public students in 2016. The lawsuit says the state has “separate but unequal” pension funding obligations as well; there is one for CPS and one for the state, and the suit asks that this be found in violation of the Illinois Civil Rights Act.

Children of color make up about 90 percent of Chicago Public Schools, while the aggregate population of the rest of Illinois public schools are predominantly white. The state’s civil rights law stipulates that “if the burdens of a state policy fall disproportionately on members of particular racial groups, the state must advance a weighty justification.”

According to the Tribune, the lawsuit is the latest fight in an ongoing battle between Mayor Emanuel’s school district and Gov. Rauner’s administration over education funding. At a news conference Tuesday afternoon, CPS officials said the lawsuit represents a last-ditch effort for a district “on the brink.”

Illinois Secretary of Education Beth Purvis said in a statement that the state is still reviewing the lawsuit.

“The governor remains focused on moving forward these recommendations and hopes that CPS will be a partner in that endeavor,” Purvis said.