Democrats have long backed charter schools as a politically safe way to give kids at low-performing schools more options. Many supported merit pay for the best teachers and holding schools accountable for test scores.

The presidential contest is proof that’s no longer the case.

If the candidates say anything about charter schools, it’s negative. Education initiatives boosted by the Bush and Obama administrations are nowhere to be found in candidate platforms.

Instead, the Democratic candidates are pitching billions of dollars in new federal spending for schools and higher pay for teachers, with few of the strings attached that marked the Obama-era approach to education.

It adds up to a sea change in Democratic thinking on education, back to a more traditional Democratic approach emphasizing funding for education and support for teachers and local schools. Mostly gone is the assumption that teachers and schools are not doing enough to serve low-performing children and that government must tighten requirements and impose consequences if results do not improve.

As a senator, Joe Biden said private school vouchers might help improve public schools. As vice president, he was atop an administration that made support for charter schools a requirement to access federal grant funding. But when asked about charters — privately run, publicly funded schools — during a recent forum with the American Federation of Teachers, Biden sounded a negative note.

“The bottom line is it siphons off money for our public schools, which are already in enough trouble,” he said.

Sen. Cory Booker of New Jersey has been a prominent backer of charter schools and helped bring them to Newark when he was mayor. But last month in Iowa, he, too, emphasized their downsides.

“I’m a guy who believes in public education and, in fact, I look at some of the charter laws that are written around this country in states like this, and I find them really offensive,” he said, according to video posted by the Hill. “They’re not about local communities finding solutions that work. They’re about raiding public education and hurting public schools, and that’s something that’s unacceptable and for me I will fight against.”

Sen. Bernie Sanders (I-Vt.) went further, calling for a halt to all federal funding for charter schools, and an outright ban on for-profit charters.

Instead, candidates are proposing spending for initiatives such as raising teacher pay.

“People in the Democratic primary are moving to a new agenda that will actually address improving our schools by improving the quality of the workforce by paying people decently,” said Neera Tanden, president of the Center for American Progress, a liberal think tank.

She noted that charters educate just 6 percent of all public school students and are concentrated in urban areas, and suggested they have been oversold. “Charters have not proven to be the one thing you do to improve public schools across America,” she said.

Sen. Kamala D. Harris of California and former housing secretary Julián Castro proposed new federal spending to raise teacher salaries. Biden, Sanders and others want big increases in funding for Title 1, which sends dollars to schools with students from low-income families. Several candidates want to boost funding for school infrastructure projects.

It’s an unsettling development for advocates of the structural changes that have fallen out of favor, and a sharp turn from where many Democrats were just a few years ago. Former presidents George W. Bush and Barack Obama had pushed a bipartisan drive for accountability, and charter schools were the answer for Democrats who opposed private school vouchers but wanted to offer other options to children — often children of color from low-income families — assigned to low-performing schools. They were important to some civil rights leaders and became a central plank in the drive for school accountability.

But by the end of the Obama administration, many parents — to say nothing of administrators and teachers — had tired of testing and opposed consequences set up under the No Child Left Behind law. Then came Education Secretary Betsy DeVos, whose top priority is promoting school choice and who is so unpopular with Democrats that candidates fear supporting anything remotely associated with her agenda.

The shift was reinforced last year by teacher strikes that focused public attention on educators’ low pay. And now the nation’s two largest teachers unions, working to capitalize on the public mood, are dangling potentially powerful endorsements in the presidential race.

In the 2016 election, the two unions contributed a combined $64 million to candidates, party commissions and outside spending groups, according to OpenSecrets, which tracks political spending.

The National Education Association, the country’s largest union, is hosting a forum for Democratic candidates July 5 at its massive annual meeting, and at least a half-dozen candidates have confirmed they will attend.

The American Federation of Teachers has been hosting candidate forums throughout the country, inviting contenders to spend a day with teachers and then answering questions town hall-style.

At the town hall with Biden last month, AFT President Randi Weingarten was so warm and complimentary that it left some with the impression she was laying the groundwork for an endorsement.

“Vice President Joe Biden was our north star in the last administration,” she said. “We didn’t always get along with the Obama administration positions on education, but we had a go-to guy who always listened to us.” She added: “He’s with us because he is us.”

During the Obama administration, the National Education Association was so angry it called for Education Secretary Arne Duncan to resign, and the other big teachers union, the AFT, came close.

When he was vice president, Biden spoke in favor of the education initiatives that the Obama administration pushed. Before that, he spoke warmly about the idea of private school vouchers.

In a 1997 speech on the Senate floor, he said he was questioning his own conclusion that it was unconstitutional to send tax dollars to religious schools. He also said he was no longer persuaded that diverting tax dollars to private schools would hurt public schools.

“When you have an area of the country — and most often here we are talking about inner cities — where the public schools are abysmal or dysfunctional or not working and where most of the children have no way out, it is legitimate to ask what would happen to the public schools with increased competition from private schools,” he said. “Is it not possible that giving poor kids a way out will force the public schools to improve and result in more people coming back?”

In an interview, Weingarten said she was more concerned about Biden’s positions today than his record or past views.

“Redemption is sometimes one of the most important things a person can do,” she said. “Experience brings judgment and changing circumstances are really important.”

During the Obama administration, she said she called Biden to complain that the administration was becoming “more and more anti-teacher,” and went to him after Obama endorsed a decision in 2010 by a Rhode Island school board to fire the entire faculty of a troubled school. She said Biden responded and got federal mediators involved, which led to the rehiring of the teachers. “That was his doing,” she said.

“You can have an honest conversation with Joe Biden, and that was really refreshing,” she said. “He would go to bat for us.”

The shift underway has Democrats who support charter schools and related policies nervous. Democrats for Education Reform is circulating results of a poll that show support for charter schools is higher among African American Democrats than whites. But overall, the poll found just 37 percent of Democratic primary voters have a favorable view of charters.

Some like-minded Democrats are working on something they call the Kids New Deal, hoping to find a candidate to support it. The centerpiece of the proposal is to make children a “protected class” under the law, which would make it easier for them to file lawsuits challenging, for instance, tenure for teachers, on the grounds that it hurts children.

“The goal here is to outflank the teachers unions from the left and not from the right,” said Ben Austin, a longtime education restructuring advocate.

Democrats who support restructuring need to find someone to take up their case, said Angela Kuefler, a Democrat and education consultant who studies public opinion on these issues. So far, they’ve had little luck.

“That’s just a testament to how much the politics on the Democratic side have changed since Trump and Betsy DeVos,” she said. “It’s a way to oppose the president — to be against charter schools.”