Students in the nation’s only federally funded school voucher initiative performed worse on standardized tests within a year after entering D.C. private schools than peers who did not participate, according to a new federal analysis that comes as President Trump is seeking to pour billions of dollars into expanding the private school scholarships nationwide.

The study, released Thursday by the Education Department’s research division, follows several other recent studies of state-funded vouchers in Louisiana, Indiana and Ohio that suggested negative effects on student achievement. Critics are seizing on this data as they try to counter Trump’s push to direct public dollars to private schools.

Vouchers, deeply controversial among supporters of public education, are direct government subsidies parents can use as scholarships for private schools. These payments can cover all or part of the annual tuition bills, depending on the school.

Education Secretary Betsy DeVos has long argued that vouchers help poor children escape from failing public schools. But Sen. Patty Murray (Wash.), the top Democrat on the Senate Education Committee, said that DeVos should heed the department’s Institute of Education Sciences. Given the new findings, Murray said, “it’s time for her to finally abandon her reckless plans to privatize public schools across the country.”

DeVos defended the D.C. program, saying it is part of an expansive school-choice market in the nation’s capital that includes a robust public charter school sector.

“When school choice policies are fully implemented, there should not be differences in achievement among the various types of schools,” she said in a statement. She added that the study found that parents “overwhelmingly support” the voucher program “and that, at the same time, these schools need to improve upon how they serve some of D.C.’s most vulnerable students.”

The D.C. program serves about 1,100 students, giving them up to $8,452 to attend a private elementary or middle school and up to $12,679 for high school. Participating private schools must be accredited by 2021 but otherwise face few requirements beyond showing that they are in good financial standing and demonstrating compliance with health and safety laws.

D.C. students who used vouchers had significantly lower math scores a year after joining the program, on average, than students who applied for a voucher through a citywide lottery but did not receive one. For voucher students in kindergarten through fifth grade, reading scores were also significantly lower. For older voucher students, there was no significant difference in reading scores.

For voucher recipients coming from a low-performing public school — the population that the voucher program primarily aims to reach — attending a private school had no effect on achievement. But for voucher recipients coming from higher-performing public schools, the negative effect was particularly large.

The analysis reviewed data for more than 1,700 students who participated in the lotteries from 2012 to 2014.

[Quality controls lacking for D.C. private schools accepting vouchers]

Martin West, a professor of education at Harvard, said the D.C. study adds to an emerging pattern of research showing declines in student achievement among voucher recipients, a departure from an earlier wave of research — often on smaller, privately funded scholarship programs — that skewed more positive.

“I think we need to be asking the question: Why is this happening and what should we make of it and should we care?” West said. He said weaker scores among voucher recipients may be a result of the fact that public school performance is improving, particularly in the District, where math and reading scores at traditional public and public charter schools have increased quickly over the past decade.

Kevin Chavous, a national voucher advocate who lobbied for the program as a member of the D.C. Council in 2004, said he wasn’t surprised by the findings because the study examined student performance after only one year in private school.

“These are kids that come from some of the most challenged backgrounds, and they’re just getting adjusted. It’s no question that the longer they’re in our schools, the better they do,” Chavous said. “We have to look at the ultimate judge of the quality of the program, and that’s the graduation rate and the college-going rate.” Chavous said the voucher program gave disempowered parents something they lack in many other parts of their lives: control. “That’s a landmark thing in urban America,” he said.

Over the past two decades, a pile of contradictory studies including on programs in Charlotte, Milwaukee and New York — have painted a muddy picture of how funneling public funds toward private-school tuition affects student achievement. In some cases, students receiving private-school tuition assistance modestly outperformed similar students who stayed in public schools; in other cases, including the first federal analysis of the District’s program in 2010, there was no difference.

“It’s not a picture you should hang a policy on,” said Martin Carnoy, a Stanford professor of education who has studied vouchers. The administration’s focus on choice is “diverting attention from ways to really improve schooling,” he said. “I think that’s the harm in all of this.”

School-choice advocates argue that test scores offer a limited picture of performance and that graduation and college-enrollment rates mean far more for long-term success. Several studies have shown that voucher recipients tend to do better on these measures, including in the District, where the 2010 federal analysis showed that 91 percent of students who used a voucher to attend a private school graduated on time, compared with 70 percent of those without vouchers.

The 2010 analysis also showed that parents of students who were offered vouchers, but not the students themselves, felt more confident in the safety of their schools. The new evaluation echoes that finding. The new evaluation also found that the program had no effect on parents’ school satisfaction.

[DeVos praises this voucher-like program. Here’s what it means for school reform.]

Congress created the D.C. Opportunity Scholarship Program in 2004 with the support of key local leaders, including then-Mayor Anthony A. Williams.

Advocates of the program spent the past eight years fighting for its survival under President Barack Obama, who opposed vouchers. Now they are hopeful that the White House’s staunch support for choice, coupled with Republican majorities in Congress, will enable the program to grow. Already, Trump has freed up millions of dollars in carry-over funding from previous years that officials say will allow the program to nearly triple the number of students it serves — from about 1,100 this year to 3,000 in the next school year.

More than 6,000 students, most of them African American or Latino, have used D.C. vouchers since the program’s inception.

Voucher critics often argue that sending taxpayer dollars to private schools drains public schools, which serve the vast majority of children, of necessary resources. In her statement Thursday, DeVos said that the D.C. voucher program had clearly not damaged progress in the city’s public schools.

But the D.C. voucher program is singular. Rather than diverting funds from the District’s public schools, it has brought them additional revenue. To make the program politically palatable in a city dominated by Democrats, Congress has appropriated millions of dollars a year for the city’s traditional public schools and its growing set of public charter schools.