David Letterman says 'despicable' Donald Trump proves 'anyone can grow up to be president'

Not even the chance to make fun of Donald Trump's presidential run gives David Letterman any regrets about retiring. Surprisingly, it barely seems to register on his joke radar.

When Tom Brokaw asked Letterman in a new interview if he has any feelings of missing out, the retired "Late Show" host didn't seem to feel Trump's run was all that comical.

"I understand that he's repugnant to people," Letterman said during his first television interview since retiring, on "Dateline NBC: On Assignment." "The men putting together the Constitution, witnessing this election, wouldn't they have just said, 'That's part of the way we set it up. Good luck?'"

He then added, "There's nothing illegal going on. It's just he's despicable."

Letterman was able to find the silver lining (and inject a little humor) in the subject of Trump's run.

"And in this very school," the retired host said while he and Brokaw spoke in front of a school, "and everybody's school, you hear, 'The great thing about America is anybody can grow up to be president.' Oh, jeez."

The full interview will air on "Dateline: On Assignment" this Sunday at 7 p.m. on NBC.

Watch the excerpt from the interview below: