In the latest public relations headache for Success Academy, a major donor and charter school supporter made racially charged comments about an African-American New York state senator.

Daniel Loeb, who chairs Success Academy’s board, posted a sharp critique on Facebook Thursday night of Sen. Andrea Stewart-Cousins, whose opposition to policies that support charter schools he said harms black students. Stewart-Cousins did “more damage to people of color than anyone who has ever donned a hood,” Loeb wrote, apparently referring to the Ku Klux Klan costume.

Loeb — who is also a board member of the pro-charter group StudentsFirstNY and a major donor for the charter sector — quickly apologized after the New York Times picked up on the comments. He said he regretted the language he used to express his “passion for educational choice,” according to the Times.

Success Academy CEO Eva Moskowitz denounced Loeb’s comments on Friday — while suggesting that she also believes that his critique of charter school detractors has some merit.

“An apology for these comments was appropriate and absolutely necessary,” Moskowitz said in a statement. “While it is true that anti-charter policies hurt children of color, we must recognize there are electeds who in good faith hold differing positions on schooling.”

The dustup could be another test for Moskowitz within her network as it prepares to open the school year. Last year, her teachers pressed her to distance herself from the Trump administration, which considered her for the education secretary role. Instead, Moskowitz said that she would oppose Trump policies that hurt the families the schools serve, but would work with the administration to advance school choice. She even had Ivanka Trump and Paul Ryan, speaker of the U.S. House of Representatives, tour her schools.

Loeb’s comments are also drawing fire from the teachers union president, who praised Stewart-Cousins as a “tireless champion of the school children of this state.”

“She has never wavered in her support for public schools,” said United Federation of Teachers President Michael Mulgrew. “Attacking her — particularly in such incendiary terms — is a despicable act.”