Filmmaker David Guggenheim unleashed a wealth of controversy last September with the release of his documentary “Waiting For Superman,” which tackled the failures of the American public education system. But five months later, Guggenheim said the backlash against him from teachers’ unions remains strong, and he blames them in large part for not allowing improvements to be implemented into the system.

“The hardest part (of making the film) was the unions and the teacher's union is one (part) of why we aren't going as fast as we can with the reforms,” Guggenheim told FOX411’s Pop Tarts at the Directors Guild of America (DGA) Awards in Hollywood on Saturday night, where he was nominated for Outstanding Achievement in Documentary Feature filmmaking. “And that was a difficult piece because I believe in unions – I'm a member of the Director's Guild, the union tonight.  That's a difficult thing to sort of dissect that issue.” 

The teachers’ unions in question were not immediately available for comment.

But even though change isn’t happening as fast as Guggenheim would like, he takes pride in the fact the film simply sparked fodder for debate.

“When we started out making ‘Waiting for Superman’ we were saying how do we get people to even pay attention to the issue of public education?  It seemed like an issue that people had forgotten,” he said. “It seemed like an issue where people were like, 'oh no we can't go there.’ The fact that people are talking about it now is actually the most gratifying.”

 “Also, in a lot of districts now they (government officials) are talking about how to reform teacher tenure, how do you evaluate teachers, how do you keep great teachers? That's in the conversation now, and it really wasn't.  The Secretary of Education is having a meeting with many of the districts this week in Colorado, talking about how do you make these big changes, the President had a speech about it  the other night. Ten minutes of his speech was about education.  That's very gratifying-- if we were a small part of that, then that's pretty special.”

But despite having made so many waves with this crucial issue, Guggenheim doesn’t have any immediate intentions to tackle any new problems in a film and thus spark any new controversial firestorms.

“I’m going to have fun tonight and I’m going to sleep,” he added with a smile.