WASHINGTON -- South Bend, Ind., Mayor Pete Buttigieg, a 2020 Democratic presidential candidate, said at an Iowa event Wednesday that the National Rifle Association is “in charge” of President Donald Trump. “Apparently they have him by the… base,” Buttigieg said to laughter from the crowd.

Buttigieg criticized the president for reversing his stance on background check legislation following two mass shootings in Texas and Ohio this month. Trump has seemed to change his mind in multiple public statements since the shootings about whether he supports legislation that would expand background checks.

More:Trump reverses again on gun background checks

Initially, Trump came out strongly in support of such a bill, saying “this isn't a question of NRA, Republican or Democrat."

But the president appeared to backtrack in recent days when he emphasized his support for the Second Amendment: “We can’t make it harder for good, solid, law-abiding citizens to protect themselves,” he said at a campaign rally in New Hampshire last week.

Then on Tuesday, he mentioned that background checks are already “very strong” now and called again for mental health issues to be addressed in combating gun violence.

More:Are mass shootings a 'mental illness problem'? Experts say the link is vastly overstated

“Did you see that today, apparently the president—even this president—felt compelled to at least pretend to be for background checks after what happened,” Buttigieg said Wednesday. He added, “And a 30-minute call with the president of the NRA reminded him who’s in charge. Apparently they have him by the… base. And he just can’t stand up to them, and that puts American lives at risk.”

Reports that Trump told NRA leader Wayne LaPierre background checks were off the table surfaced Tuesday evening. While Trump acknowledged the phone call, and the NRA confirmed it happened, he denied ever telling LaPierre that he would not pursue background check legislation.

“I have an appetite for background checks,” Trump told reporters on Wednesday afternoon. “We’re going to be doing background checks."

Buttigieg favors universal background check legislation, and has also advocated for a gun licensing system and a ban on military-style assault weapons.

"Let's at least get the background checks done. I don’t think it's enough, but let's get the background checks done," Buttigieg said Wednesday.

Contributing: Nicholas Wu, Michael Collins and John Fritze