David Letterman told New York Magazine that late night hosts have an "obligation" to take on President Donald Trump because comedy is "one of the ways that we can protect ourselves" from the president.

The former host said he doesn't pay much attention to late night TV these days, but he wouldn't have to watch long to see his successor, Stephen Colbert, taking on Trump to great success.

"Trump entered the room and did the traditional handshakes with everybody," Colbert said in his opening monologue after Trump's speech to congress last week. "So many handshakes, such little hands."

"The Late Show with Stephen Colbert" has found more viewers as Colbert has grown more vocal against Trump. The CBS telecast topped its competitors in February -- the network's first late night victory in February sweeps since 2010.

And while "The Late Show" undoubtedly skewers the commander in chief, Colbert mostly keeps talk of Trump to the top the broadcast. His celebrity interviews are -- for the most part -- free of politics.

Related: Colbert nabs late night's top spot for 2nd time this week

Letterman, who retired in 2015 after 33 years in late night, said he'd be "exhausted" from joking about Trump if he was still on the air.

He also said he would have gone harder on Trump than "Tonight Show" host Jimmy Fallon did when he was criticized for tussling Trump's signature hair in an interview last September.

"I don't want to criticize Jimmy Fallon, but I can only tell you what I would have done in that situation: I would have gone to work on Trump," Letterman said. "The thing about it is, you don't have to concoct a complicated satirical premise to joke about Donald Trump. It's not, 'Two guys walk into a bar...'"

While Fallon has lost his late night ratings lead to Colbert, he's still winning with key viewers 18 to 49, a demographic beloved by advertisers -- and Seth Meyers, who follows Fallon, is already going all-in on Trump.

Related: Jon Stewart's message for the media: Stop whining about Trump

Letterman added that it's important to keep pressure on the president because Trump has "such thin skin."

His successor -- and many others on late night -- seem to be doing just that.