School-choice philanthropist Betsy DeVos is set to become Donald Trump’s secretary of education. The school choice movement that Trump has embraced is bipartisan; centrist Democrats and Republicans both tend to support public charter schools. But DeVos, a former chairwoman of the Michigan Republican Party, represents the most conservative corner of the movement. She and her husband have funded a series of efforts to turn public school funding into vouchers for students to attend private schools. They have also fought to prevent charter schools, including for-profit charter schools, from being more tightly regulated.

The DeVos appointment signals that Trump is serious about the $20 billion school voucher plan he rolled out on the campaign trail. The proposal would redirect huge swaths of the federal education budget away from school districts and toward low-income parents, allowing them to spend a voucher at a public or private school of their choice, potentially including for-profit, virtual, and religious schools.

On the plus side, families like having choices. In cities with strong regulations on who can open a public charter school and how it operates, such as New York and Boston, school choice has driven achievement gains for kids. Some private school voucher programs have even produced mild reductions in the racial and socio-economic segregation of poor students of color. Still, the potential downsides are significant. Recent studies of voucher programs in Louisiana and Ohio found that students who use vouchers to attend a private school score, on average, lower on standardized tests than demographically similar students who do not use vouchers. In New Orleans, two years after winning a private school voucher, the average student had lost 13 points of learning in math. The reasons why point to the shortcomings of the Trump proposal. The modest size of the voucher, about $5,500 in Louisiana, was not large enough to persuade the most exclusive private schools to accept a more challenging student population. Many of the private schools that did accept vouchers had experienced previous enrollment declines, indicating they were unpopular with parents who could afford to pay tuition on their own.

Public school student achievement in New Orleans has improved in recent years, in part because of increased family choice among nonprofit charter schools. But according to Douglas Harris, an economist at Tulane University and director of the Education Research Alliance for New Orleans, “We’ve never seen an effect as negative as the private school voucher program.” Harris doesn’t expect this evidence to dissuade Team Trump. “Of all the ideas I’ve heard bandied about in various policy areas, this is the one most likely to happen. Trump is talking about it and clearly thinks it’s a good idea. Republicans love this. Most policy is going to be driven by Congress, probably even more so under Trump than any previous administration. This is what they want to do. The stars are aligned.”

Trump first rolled out the voucher plan out in early September, on the day he visited the Cleveland Arts and Social Sciences Academy, a for-profit charter school that received grades of D and F on a 2014–15 state report card, for failing to help its students improve academically. (In general, for-profit charter schools have posted dismal academic outcomes.)

It was a fitting setting. Trump’s voucher plan could be a windfall for companies hoping to make money from our public education system. To craft its education platform, the Trump campaign tapped Rob Goad, an aide to Republican Rep. Luke Messer of Indiana. Messer is a defender of the for-profit higher-education sector that President Obama fought to rein in. On K-12 issues, Messer introduced legislation known as Title I portability, which seems to have inspired Team Trump. It would redirect funding away from Title I of the Elementary and Secondary Education Act, a piece of civil rights legislation championed by President Lyndon B. Johnson. Currently, those billions flow exclusively to public schools that serve large percentages of poor children. The rationale, backed by decades of social science, is simple: It is most expensive and difficult to provide a quality education in environments of concentrated poverty, so schools that do so deserve extra federal support. The Messer plan would, instead, use Title I to provide individual families with vouchers. His proposal goes further than portability plans introduced by other Republicans, in that it would allow religious and private schools to participate, not just public charter schools.

Portability opens the door to for-profit schools, too, including the online-only virtual charter schools where, according to one large study, the average child learns far less than he or she would at a traditional brick-and-mortar school.

“Trump’s coalition is very much built around rural voters, and they don’t have charters or many private schools,” Harris says, because there are fewer school choices in regions with low population density. “So the online virtual piece is very likely to be part of this.”

Kevin Carey, director of education policy at New America, the nonpartisan think tank (and partner with Slate on Future Tense), agrees. He points out that vouchers could be made available to home-schoolers, a largely conservative constituency that relies on online education tools. “In all kinds of ways big and small, there will be a push to open up education funding to for-profit operators,” Carey predicts.

How will it be paid for? The math is pretty dicey. With 11 million school-aged children living in poverty, $20 billion in federal funding equals just a $1,800 voucher per student. That’s far too little to pay for a year of education in any school, let alone one that hopes to eke a profit out of the arrangement. In his Cleveland speech, Trump said he hoped that states would also choose to voucherize their education funding, giving families up to $12,000 to spend per child. To encourage states to do that, Trump could follow President Obama’s lead and create an incentive. Obama’s signature education program, Race to the Top, gave extra federal dollars to states that agreed to a variety of reforms, most prominently, holding teachers accountable for student test scores. Trump could use a similar program design to push states to accept vouchers.

Of course, many state-level policymakers don’t want to do that. The constituency for Title I funding as it currently exists is strong, comprising almost every elected Democrat in the country, as well as bipartisan groups such as school boards. President Obama said he would veto any education bill that included Title I portability, because it would lead to reductions in funding for the traditional public schools currently serving the poorest kids.

But it wouldn’t be impossible for Trump to find state-level partners. “To pull it off, he would have to find an enthusiastic governor and legislature who want to get on board with a big privatization experiment,” Carey said. “I imagine out of 50 states, he could find one.” Would privatization be a cost-efficient way to help kids learn more? It’s doubtful.