After appearing on his show more than 30 times, David Letterman now says that Trump is a "psychotic soulless bastard".

"I think he just liked being on TV. I had no sense that he was the soulless bastard that he's turned into," Letterman told The Hollywood Reporter.

"He used to be kind of like the boob of New York that pretended to be wealthy, or we thought was wealthy, and now he's just a psychotic," he added, asking "what went wrong?"

On the face of it, the only thing that "went wrong" is that Trump stopped pandering to Democrats.

It's an extraordinary coincidence that Letterman only began to view Trump as a psychotic soulless bastard after he ran as a Republican and won.