Senator Bernie Sanders of Vermont said in an interview released Friday that he was surprised by how unprepared Michael R. Bloomberg seemed in the Democratic presidential debate in Las Vegas this week, and predicted that President Trump would “chew him up and spit him out” in a general-election debate if the former New York mayor won the nomination.

In an excerpt from the interview, recorded Thursday and set to be broadcast on CBS’s “60 Minutes” Sunday night, the correspondent Anderson Cooper asked Mr. Sanders whether he was surprised by Mr. Bloomberg’s struggles to answer “some very basic, obvious questions.” Mr. Sanders, the Democratic primary’s current front-runner, said he was.