The former president reportedly brushed over the effects of his incendiary language, including use of terms such as “enemy of the people” when referring to the media.
The new book by ABC News’ chief Washington correspondent Jonathan Karl, titled Tired of Winning: Donald Trump and the End of the Grand Old Party, is the latest piece of work to feature a collection of bombshell revelations about the former president.
Discussing the book – which is due to be released at midnight on Tuesday – Mr Karl recalled discussing the actions of Mr Trump’s zealous supporters with him.
"I remember a conversation I had with him when we had the mass shootings in El Paso and Pennsylvania and Dayton in short order, and there were real concerns there would be more," Mr Karl told MSNBC on Monday.
"And he’s using this language. This language out of the Third Reich — ‘enemy of the people.’ I said, ‘Aren’t you concerned the people will take your words to heart? Aren’t you concerned they will act on them?’
“And without missing a beat, he said, ‘I hope they take my words to heart. I believe the press is the enemy of the people’.”
Mr Karl continued: “Maybe it’s an inability to have any kind of empathy or understanding of the consequences of your words, but that is consistent. That’s not new."
Other claims that feature in Mr Karl’s book include that the former president once reportedly boasted of being “complimented” on the size of crowds at his political rallies – unaware he was being compared to Adolf Hitler.
Following a conversation with then-chancellor of Germany Angela Merkel, Mr Trump said she had told him that there was “only one other political leader who ever got crowds as big as mine”.
According to Mr Karl, the congressman who revealed this to him – an ally of Mr Trump – had been “absolutely blown away” by the former president’s apparent misunderstanding. Mr Trump’s campaign has denied these claims – branding Mr Karl as “talentless”.
It comes after Mr Trump recently drew ire from historians following a Veterans Day speech – which also prompted comparisons to dictators such as Hitler – with his use of the word “vermin” to refer to his political opponents.