David Letterman: Donald Trump is a 'damaged human,' and I would have 'gone right after him'

If David Letterman could have held onto another year in late night, he would've had a really good time taking on Donald Trump.

In previous years, Letterman enjoyed having Trump on his show. They went toe-to-toe several times. In fact, Hillary Clinton uses a clip from a 2012 "Late Show" interview in which Letterman calls out Trump for having his Macy's clothing line made in China in one of her campaign commercials (watch it below).

"Nobody took him seriously, and people loved him when he would come on the show," Letterman, 69, said in a new interview with The New York Times. "I would make fun of his hair, I would call him a slumlord, I would make fun of his ties. And he could just take a punch like nothing. He was the perfect guest."

But that was before he became a serious contender for the American presidency. In that capacity, Letterman has ceased to find the real estate mogul so funny. Letterman mentioned that he has been shocked by Trump's comments about immigrants, and the time he mocked a reporter with a disability.

"If this was somebody else - if this was a member of your family or a next-door neighbor, a guy at work - you would immediately distance yourself from that person," the retired late-night host said. "And that's what I thought would happen. Because if you can do that in a national forum, that says to me that you are a damaged human being. If you can do that, and not apologize, you're a person to be shunned."

When asked about Jimmy Fallon's recently criticized softball interview with Trump, Letterman said he would definitely have been harder on the Republican candidate.

"If I had a show, I would have gone right after him," Letterman, who is promoting his involvement in the National Geographic Channel series "Years of Living Dangerously," told the newspaper.

"I would have said something like, 'Hey, nice to see you. Now, let me ask you: what gives you the right to make fun of a human who is less fortunate, physically, than you are?'" he continued "And maybe that's where it would have ended. Because I don't know anything about politics. I don't know anything about trade agreements. I don't know anything about China devaluing the yuan. But if you see somebody who's not behaving like any other human you've known, that means something. They need an appointment with a psychiatrist. They need a diagnosis and they need a prescription."