"I hate to say that I told you so, but I told you so. When I became secretary of education I said the teachers' unions were the worst force in America except for organized crime, and it was a close call," Bennett told Fox News "Outnumbered."
"And I think [with] this last year of COVID and this resistance in the unions now they have come out this way.
Bennett encouraged parents concerned about their children’s education to run for the school board.
"Take a look at Loudoun County, they are making a difference," Bennett said.
Bennett reacted to the country’s largest teachers union's move to undermine the left-wing talking point that critical race theory is not taught to children -- by voting promote it and arguing it is "reasonable and appropriate" to use CRT in social studies classes.
The National Education Association has approved a plan to "publicize" critical race theory and dedicate a "team of staffers" to assist union members looking to "fight back against anti-CRT rhetoric."
New Business Item 39 also declares that the union opposes bans on critical race theory and the New York Times’ controversial 1619 Project – which roughly half the U.S. states have already implemented.
The move comes as districts around the country and liberal pundits have attempted to fend off anti-CRT parents by telling them the curriculum is too complex for K-12 students and is only taught to students in graduate-level courses.
That claim is made despite evidence that critical race theory seminars are being offered to teachers and administrators and examples of CRT-themed topics are being introduced in some classrooms.
Conservative lawmakers have already secured bans on CRT in roughly two-dozen states, with Iowa going as far as to declare it "discriminatory indoctrination." And the topic on its own has prompted impassioned public comments at school board meetings around the country.
Critics say CTR is a racist philosophy that encourages stereotyping and labeling while highlighting divisiveness and anti-American rhetoric rather than unity and the virtues of the founding documents.
The NEA represents more than 2 million members – well over half of the 3.2 million public school teachers the U.S. Department of Education estimated were working in the country last year.
The union did not immediately respond to a Fox News request for comment.
Bennett explained how teacher unions are getting in the way of school choice.
"The other thing is school choice," he said. "They are not doing it the way you want it, as a parent, your school, you should be able and now you are able to leave that school and go to another school."
"This is obnoxious behavior on the part of the teachers’ unions," Bennett continued. "Just one caution -- I think Shannon (Bream) and Emily (Compagno) would agree with this. States are writing these anti-critical race theory laws, careful that they are not overbroad. They are going to get challenged on free speech issues and so on. Nevertheless, this fight is worth it. This is a fight about our children and our future."
Fox News' Michael Ruiz contributed to this report.