WASHINGTON (AP) — Expanding charter schools around the country is losing support among Americans, even as President Donald Trump and his administration continue to push for school choice, according to a survey released Tuesday.

Trump campaigned on a promise to dramatically improve school choice — charter schools and private school voucher programs — and his Education Secretary Betsy DeVos has made it a priority. But so far the message does not appear to have hit home with the public.

About 39 percent of respondents favor opening more charters — schools that are funded by public money, but usually operated independently of school districts — according to the survey by Education Next, a journal published by Harvard’s Kennedy School and Stanford University. That’s down from 51 percent last year.

Supporters of charter schools had feared that Trump’s polarizing rhetoric could hurt the school-choice movement.

But the authors of the report say the decline in support for charters can’t be linked directly to Trump. They say support for charters slipped almost equally across party lines: by 11 percent among Democrats and by 13 percent among Republicans.

They also emphasize that private school vouchers and voucher-type programs, championed by Trump, have seen stable support and declining opposition. Finally, when respondents were told that Trump was advocating for charter schools, overall support increased by 6 percentage points.

“We can’t say definitively what is responsible for the decline,” said Martin West, associate professor of education at Harvard University and a co-author of the report. West speculated that the drop may have been caused by continued opposition from teachers unions and many Democrats plus debates over charters’ effectiveness.

“These developments may have led to a souring of the charter brand,” West said.

Meanwhile, opposition to publicly funded vouchers that help parents pay private school tuition dropped from 44 percent last year to 37 percent; 45 percent of respondents currently favor the idea. When it comes to tax credit-funded scholarships, resistance fell from 29 percent to 24 percent, while support was at 54 percent now.

Proponents of charter schools are not discouraged. Nina Rees, president of the National Alliance for Public Charter Schools, says the drop in popularity was due to “expensive, sustained, and coordinated campaigns to discredit charter schools, led by teachers’ unions and special interests that feel threatened by families having a choice in public school.”

Rees said that more than 300 public charter schools opened last year, with a total over 6,900 charter schools serving over 3 million students across the country.

“The opinions about charter schools that matter most are the opinions of parents and students who have chosen charter schools,” Rees said.

To others, the Trump effect is more apparent. On the campaign trail, Trump spoke of funding a $20 billion school choice program and has proposed major cuts to long-standing K-12 programs, such as teacher preparation and after-school classes, while requesting more funding for charters and vouchers. DeVos has faced criticism from the left for promoting solely school choice and paying little attention to public schools.

Robin Lake, director of the Center on Reinventing Public Education, said the Trump administration’s rhetoric has only deepened partisan tensions around charter schools.