Presumed Republican presidential nominee Donald Trump addresses members of the National Rifle Association at their annual meeting in Louisville on May 20. (John Sommers II/Reuters)

Donald Trump may be the candidate that the National Rifle Association (NRA) supports in the presidential race, but on Sunday it was not at all clear whether he backs the organization's official position on guns in American schools.

During a call-in interview with "Fox & Friends," Trump gave a rather ambiguous response to a question about the issue.

“I don’t want to have guns in classrooms. Although, in some cases, teachers should have guns in classrooms,” he said. Then he offered more mixed statements about teachers and guns and schools.

I’m not advocating guns in classrooms. ... In some cases — and a lot of people have made this case — teachers should be able to have guns, trained teachers should be able to have guns in classrooms.

On Friday, Trump addressed the NRA's annual meeting. During that speech, he vowed to eliminate gun-free zones — areas where guns cannot be legally carried by most individuals — in the United States. In January, Trump told supporters at a campaign rally that he would work to eliminate gun-free zones that cover schools and military bases in the country.

The NRA backs the presence of armed guards in schools and has lobbied in support of proposals in several states that would allow teachers and other school personnel to come to work with guns. In 2013, an NRA task force released a report that recommended that teachers with firearms experience carry weapons in the nation's classrooms.

Guns have been forbidden at most schools for all but a few individuals (mostly law enforcement officers) for nearly 20 years. In 1990, then-President George H.W. Bush signed the Gun Free School Zones Act, which makes it illegal for unauthorized individuals to posses a firearm inside a school or the area around a school. The law has faced multiple legal challenges, including a 1995 defeat at the U.S. Supreme Court. However, during Bill Clinton's administration, the Justice Department sought and won a change in the law that clarified federal oversight of guns on school grounds.

Trump's likely general election opponent, former secretary of state Hillary Clinton, used her own time in front of several microphones last week to accuse Trump of pandering to the powerful gun group and its political interests.