Hillary Rodham Clinton long skirted the internal Democratic Party conflict over the best way to improve public schools. She avoided the fight between teachers unions, which want heavier investment and less blame for educators, and those who believe nonunionized charter schools should be expanded and teachers held accountable for student achievement.

But Clinton’s neutrality has started to fray.

By early October, she had pocketed presidential endorsements from both major teachers unions. Before she got the nod from the National Education Association, Clinton told a private gathering of NEA leaders that she wanted the country’s largest union to be “at the table, literally and figuratively,” as she formulates policy, according to excerpts included in an NEA publication.

At a town hall meeting in South Carolina on Saturday, Clinton was critical of public charter schools, saying “most” intentionally exclude or expel children who are difficult to educate.

Hillary Clinton answers a question from Roland Martin on TV One’s News One Now, at a town hall meeting in S.C. on Nov. 7. (Richard Burkhart/AP Images For TV One)

“Most charter schools — I don’t want to say every one — but most charter schools, they don’t take the hardest-to-teach kids, or, if they do, they don’t keep them,” Clinton said in response to questions at an event hosted by the South Carolina Legislative Black Caucus.

By contrast, she said, traditional public schools “thankfully, take everybody, and then they don’t get the resources or the help and support that they need to be able to take care of every child’s education.”

The remarks lit up the world of K-12 education policy, prompting outrage from organizations that have been fighting to expand charter schools as an alternative to traditional ones. Some alleged that the presidential hopeful is out of touch.

“That is absolutely false,” Jeanne Allen, the founder of the Center for Education Reform, said of Clinton’s claims about charters. “She sounds like an aloof, elite candidate from a bygone era, before ed reform was a reality.”

There are public charter schools with high expulsion rates, enough to prompt U.S. Education Secretary Arne Duncan to flag the problem when he addressed the National Alliance for Public Charter Schools in 2013.

Success Academy, the largest charter operator in New York City, has come under fire in recent weeks for a “got to go” list that allegedly targeted 16 students for expulsion at one of its schools. Success Academy students, who are almost entirely minority and low income, are among the highest-performing on state tests. Critics argue that Success Academy achieves that honor by expelling weak performers or those with behavioral problems, a charge the chain’s founder has denied.

Until now, Clinton’s remarks about education on the campaign trail have been largely limited to early-childhood education and college access, two issues that are relatively noncontroversial in comparison with K-12 policy.

At the town hall Saturday, Clinton was asked about a poll that showed strong support among black families for increasing school choice, including charter schools and private school vouchers.

She did not directly answer the question, but she repeatedly contrasted charter schools with “public schools,” a pattern that infuriated charter-school advocates, who say that while charters may be privately managed, they are funded with tax dollars and serve the public.

“I have for many years now, about 30 years, supported the idea of charter schools, but not as a substitute for the public schools but as a supplement for the public schools,” Clinton said.

Her remarks, combined with her earlier statements to the NEA and the endorsements of the unions, are raising concerns among elements within the Democratic Party that support policies such as merit pay, teacher evaluations and charter schools.

“There’s no doubt that we’re very troubled and concerned,” said Shavar Jeffries, president of Democrats for Education Reform. “We don’t want any sort of slowdown on the Obama legacy of expanding high-quality charter seats, particularly for families of color, many of whom are attending schools that are failing them.”

Jeffries said his organization is hoping that Clinton’s comments are an anomaly.

“Secretary Clinton has a 30-year record of being very supportive of choice and charter schools,” he said. “We’re hopeful that she will act in ways consistent with her record.”

Clinton’s record on education has not been one-sided. As first lady of Arkansas in 1982, she pushed to broaden course offerings in public schools and reduce class sizes, both ideas that are popular with teachers. But she also wanted to institute competency testing for educators — an idea that provoked a fierce pushback from the unions.

As U.S. first lady and then a U.S. senator, Clinton promoted policies the unions welcomed, including expanding preschool and after-school programs, but she also embraced public charter schools. She said parents, teachers and students all bore responsibility for academic outcomes.

“For decades, Hillary Clinton has been a strong supporter of both public charter schools and an unflinching advocate for traditional public schools, their teachers and their students,” Clinton spokesman Jesse Ferguson said when asked to explain the comments she made Saturday.

Clinton “wants to be sure that public charter schools, like traditional public schools, serve all students and do not discriminate against students with disabilities or behavioral challenges,” Ferguson said. “She wants to be sure that public charter schools are open to all students. As president, she will work to ensure there are pathways for every child to live up to their potential.”