President Donald Trump and his advisers probably didn’t expect his choice for education secretary to cause much of a fuss. After all, Rick Perry was tapped to run the Department of Energy, which he once said he wanted to eliminate. Senator Jeff Sessions, who has spent his career attacking voting rights, was up for attorney general. Scott Pruitt, nominated to run the EPA, has sued the agency at least 14 times. Even Ben Carson was offered a job.

And yet, Betsy DeVos turned out to be Trump’s most controversial cabinet pick. It came as a surprise to many in Washington, but it didn’t come out of the blue.

Teachers unions, which have given hundreds of millions of dollars to the Democratic Party over the years, led the fight against DeVos, a billionaire Republican donor and education philanthropist. The National Education Association and the American Federation of Teachers released a joint letter decrying the “two decades she has spent attempting to dismantle the American public school system.”

“[DeVos] and her family have spent millions to promote failed private school vouchers and unaccountable for-profit charter schools while working to destabilize and defund public education,” the unions wrote. “This is a dangerous direction that will do nothing to help our most vulnerable students and will exacerbate glaring opportunity gaps.”

DeVos bolstered the case against her with a disastrous performance at her confirmation hearing. She was confused about basic education policy debates. She showed little familiarity with federal education law, and in some cases wouldn’t commit to enforcing it. In one viral moment, she even said schools might need guns to guard against “potential grizzlies.”