President Donald Trump has repeatedly criticized an armed Broward County deputy who failed to confront school shooter Nikolas Cruz as he was massacring students and faculty inside Marjory Stoneman Douglas High School earlier this month, first calling him a "coward" on his way to the Conservative Political Action Conference on Friday.

He later explained that armed teachers would be more effective at stopping school shooters because they "love the children", insinuating that security guards and police don't have enough of an incentive to risk their lives and intervene.

And on Monday, Trump continued on this theme, saying he would have acted to stop the gunman had he been there - even if he was unarmed and facing near-certain odds of death.

"I really believe I'd run in there even if I didn't have a weapon," Trump told a gathering of governors at the White House.

"And I think most of the people in this room would have done that, too."

Trump also told the governors he ate lunch last weekend with leaders of the National Rifle Association, according to the Hill

"Don't worry about the NRA," Trump told the governors.

"They're on our side."

Trump has been criticized by his political opponents for receiving several draft deferments during the Vietnam War.