HOUSTON (AP) — Echoing one of his top Democratic presidential rivals, Joe Biden is promising he would appoint a teacher as secretary of education if he wins the nomination and defeats President Donald Trump.

“We don’t treat you with dignity,” Biden told thousands of public school teachers gathered for the National Education Association convention in Texas. “If I am president, it will change on day one.”

The National Education Association forum took place Friday. Watch in the video player above.

The former vice president’s pledge was part of a campaign forum that featured almost half the Democratic field promising sweeping changes to federal education policy, with more than a few taking aim at current Education Secretary Betsy DeVos.

Massachusetts Sen. Elizabeth Warren, herself a former public school teacher and law school professor, already had promised she’d nominate a federal education chief with classroom experience. Taking the stage after Biden on Friday, she repeated the pledge with glee.

“Betsy DeVos need not apply,” Warren said, drawing a roar.

DeVos has long been among Democrats’ favorite targets in Trump’s Cabinet. Hailing from a wealthy family of conservative activists, she has spent decades advocating for an expansion of charter schools and taxpayer-financed vouchers for private schools. She had no previous professional education experience.

Yet the challenge for Democratic presidential candidates is how to stand out, beyond hammering Trump and DeVos, as they vie for support from the influential NEA and its 3 million members, a roster that makes it the nation’s largest union.

Warren and New York Bill de Blasio took aim at high stakes testing. Biden and Vermont Sen. Bernie Sanders touted their promise to triple federal funding for Title I schools, campuses that are identified as having students with economic and social challenges.

Washington Gov. Jay Inslee noted he’s won pay raises for educators in his state.

Ohio Rep. Tim Ryan and Minnesota Sen. Amy Klobuchar emphasized that their national infrastructure priorities include massive investments in public schools.

WATCH: How 2020 presidential candidates would address ‘albatross’ of student debt

Julian Castro, who served as housing secretary under President Barack Obama, noted his work expanding affordable housing, describing the approach as a key to reducing de-facto segregation in public schools.

Perhaps the most obvious deviation came on charter schools, campuses that are financed with tax dollars but typically left free from the management of traditional public school systems.

Former Texas Rep. Beto O’Rourke tracked the rest of the Democratic field by panning for-profit charter schools. “Not a single dime in my administration will go to them,” he promised. But, he said, “There is a place for public, non-profit charter schools.”

The comment drew a few boos and otherwise was met with silence from an audience that was otherwise boisterous throughout the afternoon forum.

De Blasio did not single out O’Rourke or any other Democrat, but said “too many Democrats have been cozy with the charter schools,” offering the argument that they siphon money away from traditional public education. “I hate the privatizers and I want to stop them,” he said.

Neither Biden nor Harris on Friday mentioned their recent back-and-forth over busing as a way to combat racial segregation in America’s schools.

Harris had a breakout moment in the first Democratic debates last week when she hammered Biden for his recent comments about working with segregationist senators in 1970s and for opposing federally mandated busing in local school systems.

Biden has insisted that he never opposed voluntary busing enacted by local officials — though the controversy in Washington in his early years as a Delaware senator was over the federal government’s role. And, as a young senator, Biden publicly called busing an “asinine concept.”

Harris, meanwhile, has since the debate described her current position on busing by taking a position similar to the one she criticized Biden for carving out.

Asked in Iowa whether she would support federally mandated busing in 2019 to combat de facto segregation that remains in some U.S. school systems, Harris replied, “I think of busing as being in the toolbox of what is available and what can be used for the goal of desegregating America’s schools.”

Asked to clarify whether she supports federally mandated busing, she replied, “I believe that any tool that is in the toolbox should be considered by a school district.”