WASHINGTON (AP) — The head of one of the country's leading teachers' unions charged Thursday that school choice, a key policy agenda of the Trump administration, is rooted in segregation and racism.

Randi Weingarten, president of the American Federation of Teachers, the nation's second largest teachers' group, said that decades ago school choice was used by officials in the South to resist desegregation.

Weingarten has been a fierce opponent of President Donald Trump's efforts to expand charter and private school voucher programs around the country. In her speech, she called Education Secretary Betsy DeVos a "public school denier."

"Make no mistake: This use of privatization, coupled with disinvestment, are only slightly more polite cousins of segregation," Weingarten said.

Weingarten cited the example of Prince Edward County, Virginia, which after the Supreme Court's Brown vs. Board of Education decision in 1954, tried to bypass desegregation efforts by closing down every public school and opening private schools that were off-limits to black children.

"And they did it using public money," she said. "Decades ago, the term 'choice' was used to cloak overt racism."

The comments prompted immediate criticism from school choice groups. Jeanne Allen, CEO of the Center for Education Reform, called for Weingarten's resignation.

Allen said that comparing education reform advocates to racists and segregationists "is not just ill-advised hyperbole, it is a deeply offensive, highly inflammatory insult to all the parents and people - of all races, backgrounds and regions - who have worked to bring options, opportunities and reforms to an education system that has failed them for generations."

"Weingarten's allies should disavow these comments, and America's teachers should look into their hearts, consider whether this is the type of language and leadership they want as being representative of their views and voice, and consider inviting Weingarten's resignation."

During an unrelated event in Denver, DeVos took a swipe at her opponents.

She said her school choice advocacy "has led to some . let's call it . 'excitement' on the left."

"But I consider the 'excitement' a badge of honor, and so should you," DeVos said, according to remarks released by the department. "Our opponents, the defenders of the status quo, only protest those capable of implementing real change. You represent real change."

Education Department spokeswoman Liz Hill said school choice helps level the playing field by letting students escape failing schools.

"Research shows school choice programs most benefit families from lower socio-economic backgrounds," she said in a statement. "The notion of 'privatization' is simply a scare tactic from those who are invested in defending the status quo at all costs."