Though it hasn't come up in this election, Hillary Clinton might wish she could get back the votes she cast on June 14 and Dec. 18, 2001.

On both of those days, Clinton voted for No Child Left Behind, the initially-popular but eventually-despised education reform bill.

Of course, Clinton wasn't the only one to vote for the bill. Bipartisan majorities in Congress supported it, with 91 votes in favor on June 14 and 87 in favor on December 18. Sen. Ted Kennedy, D-Mass., was one if its biggest supporters.

But teachers' unions, who vigorously opposed No Child Left Behind, aren't giving Clinton a free pass.

"There's no free passes," Lily Eskelsen Garcia, president of the National Education Association, said Tuesday. "I'm a teacher, I do a report card."

"I want to know if people learned from their mistakes [on No Child Left Behind]," she said. Eskelsen Garcia said that, in early discussions with Clinton about a potential endorsement, Clinton actually asked her questions about what teachers want. "Hillary Clinton asked the right questions. What are we going to do better next time? And maybe we better listen to the educators before we do it."

Despite her past transgressions, the National Education Association endorsed Clinton in October 2015. Bernie Sanders, who was in the House of Representatives in 2001, voted for the initial version of No Child Left Behind but voted against the final version. The union sat out the competitive 2008 Democratic presidential primary between Clinton and President Obama.

The union has 3.2 million members, making it the single largest union in the country.

Eskelsen Garcia was speaking at a panel on the 2016 elections and education hosted by the National Press Club and the Education Writers Association.

Jason Russell is a commentary writer for the Washington Examiner.