The nation’s capital is the only city in the country where the federal government gives scholarships to underprivileged children to attend private schools. The goal of the voucher program, of course, is to help ensure low-income youth aren’t tethered to their often under-resourced and under-performing neighborhood schools.

But a report released Thursday found largely negative results for students who participated in the District of Columbia’s Opportunity Scholarship Program, suggesting that many of the program’s beneficiaries might actually fare better if they turn down the private-school money.

The Institute of Education Sciences (IES) compared test scores for two groups of students: students who, through a lottery process, were selected to receive vouchers, and students who applied for yet didn’t receive them. The study compared the progress of both groups of students from spring of 2012 to 2014 and found that, a year after they applied for the scholarship, math scores were lower for students who won vouchers. What’s more, after narrowing the pool of students down to those in kindergarten through fifth grade, both reading and math scores were lower for students who won vouchers.

While students’ shortcomings in test scores—especially in math—may complicate the Trump administration’s path to elevating voucher programs, the administration remains committed to fully funding vouchers and expanding access to similar options nationwide. President Trump’s proposed 2018 budget would add $1.4 billion to school choice—which includes voucher programs and charter schools—with the goal of “ramping up to an annual total of $20 billion.” The proposed budget would also specifically allocate $250 million for “a new private school-choice program,” which likely would provide vouchers. Along with these major investments in school choice, the Department of Education as a whole would receive 13 percent less funding than last year, a reduction of $9 billion.

The release of the study Thursday gives Democratic lawmakers renewed ammo against the larger-scale voucher proposal. “When Secretary [Betsy] DeVos’s own Department’s independent research office tells her that siphoning taxpayer dollars into private schools has a negative impact on students, it’s time for her to finally abandon her reckless plans to privatize public schools across the country,” Democratic Senator Patty Murray, the ranking member of the Health, Education, Labor, and Pensions (HELP) committee, said in a statement. Democratic Congressman Bobby Scott, ranking member of the House Education and Workforce committee, said: “We know that these failed programs drain public schools of limited resources, only to deliver broken promises of academic success to parents and students. Congress must end this failed program and support the more than 90 percent of students nationwide who are enrolled in public schools."

DeVos, however, wasn’t discouraged by the latest findings, releasing a statement on Thursday indicating she hadn’t shifted her views after reviewing them. “D.C.’s traditional public schools have not suffered as a result of being part of a system that allows choice,” she said. “Rather, they have greatly improved since the 2004 inception of the District of Columbia Opportunity Scholarship Program (OSP). The study released today found that D.C. OSP parents overwhelmingly support this program, and that, at the same time, these schools need to improve upon how they serve some of D.C.’s most vulnerable students. We should demand excellence from all of our nation’s schools, regardless of their type. This Administration remains committed to fully funding D.C. OSP so that D.C.’s most vulnerable students have access to the widest array of education options possible.”

There’s nothing in the report that supports DeVos’s assertion that parents overwhelmingly support the program. Rather, it found “the program did not have a statistically significant impact on parents’ or students’ general satisfaction with the school the child attended.” The study did produce some positive findings: For example, parents of children who used school vouchers were were more likely to say that their child’s school was safe, and the parents of participating children in sixth grade or higher were more likely than those of nonparticipating children to engage in education-related activities at home. But “overwhelming” support for the voucher program itself was not indicated in the IES report.

Virginia Foxx, the Republican chairwoman of the House Committee on Education and the Workforce, acknowledged in a statement the “disappointing findings in this report,” and argued that the program would need to “step up and deliver the change that is necessary to ensure students excel from day one.” But she also stood by the effectiveness of school choice. “There’s no question improvements need to be made, but in no way should this single report diminish our support for the program or the belief that parents deserve more freedom and choices when it comes to their children’s education,” Foxx said.

A previous IES study of the D.C. voucher program, which wrapped up in 2010, found that voucher students were more likely to graduate than their non-voucher peers. Still, today’s IES report is the latest in a recent string of statewide and local studies on voucher programs that have found lackluster academic results, including a 2015 study of an Indiana program that found no improvements in reading and “significant losses in achievement” in math and a February 2016 study of Louisiana's program that found “strong and consistent evidence that students using a [Louisiana Scholarship Program] scholarship performed significantly worse in math.”

The IES evaluation is the first of three of this cohort of D.C. voucher recipients; the next one is slated for release in the next year or so and will evaluate student outcomes after two years in the voucher program. “The IES study that came out today reflects one-year findings. One-year findings, particularly with respect to math testing, are often not predictive of final outcomes,” said Serving our Children, the organization that administers the D.C. scholarship, in a statement. The organization also said previous findings about the program’s positive impact on graduation rates and college attainment “are more important indicators of, and predictors of, future success.”

DeVos has advocated for school choice, citing American students’ slow progress on national and international assessments as an argument against the status quo. She’s also indicated a reluctance to tie success in schools to empirical numbers, instead championing the idea of empowering parents to make the right decisions for their children. “I’m not a numbers person in the same way you are,” she reportedly told a researcher in late March. “But to me, the policies around empowering parents and moving decision-making to the hands of parents on behalf of children is really the direction we need to go.” While unlikely to alter DeVos’s views on school choice, the results of the study are likely to add another layer of complexity to the school-choice debate—and another reason for Democrats to attempt to thwart the Trump administration’s education agenda.