U.S. Presidential candidate Hillary Clinton at Jackson Diner in Queens, N.Y., on April 11, 2016. (Photo by Yana Paskova/For The Washington Post)

Hillary Clinton delivered plenty of applause lines Tuesday in a speech to the nation’s largest teachers union at a gathering in Washington, calling for less standardized testing, more support for vulnerable children and more respect and pay for public school educators.

“I want to say, right at the outset, that I’m with you,” Clinton said to loud cheers from thousands of delegates to the National Education Association’s annual meeting. “If I am fortunate enough to be elected president, educators will have a partner in the White House, and you’ll always have a seat at the table.”

But Clinton also signaled her willingness to challenge union orthodoxy on the lightning rod issue of charter schools, saying that there are some successful charter schools whose approaches should be studied and replicated.

“When schools get it right, whether they’re traditional public schools or public charter schools, let’s figure out what’s working and share it with schools across America,” she said to audible boos from the audience. “Rather than starting from ideology, let’s start from what’s best for our kids.”

Publicly funded but privately run and usually not unionized, charter schools have become a divisive issue within the Democratic party that Clinton — a longtime supporter of both charters and unions — has tried to bridge.

Some (including, often, teachers unions) accuse charter school advocates of trying to privatize education, wresting it from local control; supporters see charters as offering critical opportunities for some of the nation’s most vulnerable children.

Clinton rattled charter school advocates late last year when she criticized charters for leaving the task of teaching the most difficult students to traditional schools. “Most charters, they don’t take the hardest-to-teach kids, or, if they do, they don’t keep them,” she said in November in South Carolina.

Many of those same charter advocates welcomed Clinton’s remarks Tuesday. “We were happy to see her specifically affirm her support for high-quality public charter schools,” said Shavar Jeffries, president of the pro-charter group Democrats for Education Reform. “Her statements today reiterate her commitment to reform.”

NEA President Lily Eskelsen Garcia said some of her members are deeply angry about charter schools because of the way they have siphoned money away from traditional public school systems. But Eskelsen Garcia did not take umbrage at Clinton’s remarks: “There are some successful charter schools,” she said. “Let’s look at what makes them work.”

Eskelsen Garcia gave an enthusiastic introduction for Clinton, saying that her record on children and families should give teachers a reason to cast a vote for her — not just a vote against presumptive GOP presidential nominee Donald Trump.

“Hillary sees our students as whole human beings not as test scores,” Eskelsen Garcia said. “She’s fighting for preschool, she’s fighting for access to affordable college, she’s fighting for us.”

Clinton specified Tuesday that she does not support for-profit charter schools, and she emphasized that she is a strong supporter of union members’ collective bargaining rights.

“For anyone who has faced a hostile state legislature, a union-busting governor or both, help is on the way,” she said.

Clinton took the stage at the District’s Walter E. Washington Convention Center at the same time as FBI Director James Comey was announcing he would recommend she not be criminally charged for her use of a private email server while secretary of state. Clinton did not address the email server controversy during her speech.

She said she’d launch a “national campaign to elevate and modernize” the teaching profession and would push to forgive some teachers’ student loans, especially in hard-to-staff subjects like special education. And she said that the nation must do a better job of addressing students’ non-academic needs, from mental health and housing, so they can succeed in school.

The NEA endorsed Clinton in October over the objections of some of its members who favored Bernie Sanders, arguing that he would be more likely to push back against the growth of charter schools and against what many teachers see as a culture of teacher-blaming in public schools.

Some teachers in the crowd Tuesday were still frustrated with the union’s endorsement. Jeff Treistman, a middle school librarian from Seattle, said he preferred Sanders’ views on climate change, foreign policy and education, including free college tuition. He accused Clinton — who has received support from wealthy backers of charter schools — of having ties to “corporate education reform” that work against teachers.

But the crowd of more than 7,000 teachers, many clad in blue “Educators for Hillary” t-shirts, was overwhelmingly enthusiastic.

Karen Peterman, a middle school teacher from Knoxville, Tenn., said she wants to see the next president take serious steps toward reducing standardized testing, and she believes Clinton will work with the union to do that. Also, Peterman said, she can’t stomach Trump and his insults: “If Donald Trump were an eighth grader, I would send him to detention,” she said.

Clinton capitalized on that sentiment in her speech, saying Trump is a poor role model for children. “What do our kids take away from his racist attacks?” she asked.

The union’s support means not only money for Clinton’s campaign war chest but also volunteer power: The NEA boasts nearly 3 million members, and its leadership has urged those members to rally their neighbors and their communities against Trump in the general election.

Eskelsen Garcia, the NEA president, on Monday called Trump a “racist, sexist, hypocritical, egotistical thin-skinned bully” who is not fit for the White House. There is too much at stake in November for teachers to sit idly by, she said.

“You have power in choosing our next president,” Eskelsen Garcia said Monday in a keynote speech, according to a copy of her prepared remarks. “You will have a voice in shaping the future of this country. And that’s unimaginably powerful in this imperfect world. A lot of people don’t care about making a powerful choice. They stay home.”

This story has been updated.