The late-night legend took aim at his former network home and David Ellison's media company, speculating that Colbert's show was canceled for political reasons.

Speaking with his former executive producer, Barbara Gaines, in a YouTube video Friday, Letterman called the axing of The Late Show With Stephen Colbert “pure cowardice” and said he doesn’t believe the official line from CBS that the decision was purely about economics (the show has reportedly become a money-loser for the network).

"The people at CBS who have manipulated and handled this are going to be embarrassed,” the former 'Late Show' host says. “This is gutless”