The co-author of President Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE's famous business book "The Art of the Deal" says the president believes apologizing for a White House aide's insult against Sen. John McCain John Sidney McCainCindy McCain endorses Biden: He's only candidate 'who stands up for our values' Biden says Cindy McCain will endorse him Biden's six best bets in 2016 Trump states MORE (R-Ariz.) would show weakness.

"He either directly or indirectly made it clear that he didn't want Sadler to apologize because it would reflect on him," Tony Schwartz told CNN of White House aide Kelly Sadler, whose leaked comments about McCain from an internal meeting have created a controversy for the White house.

Co-author of “The Art of the Deal:” President Trump views apologizing as a weakness. “If you apologize you are wrong” https://t.co/MmfuG2le0J pic.twitter.com/bN6Gv8rH1p — Anderson Cooper 360° (@AC360) May 15, 2018

Sadler said in the meeting that McCain's opposition to Trump's nominee for CIA director "doesn't matter" because he's "dying anyway," according to comments first leaked to The Hill.

ADVERTISEMENT

The president and the White House have yet to give an official apology for the remarks against the veteran senator, who is battling brain cancer. Trump has previously mocked McCain for being captured in Vietnam.

Schwartz, who spent months of one-on-one time with Trump while writing their 1987 bestseller, says that in Trump's mind, "if you apologize you are wrong."

"I don't even think it's a calculation or an analysis or an opinion, I think it's an impulse and an instinct," Schwartz said. "Emotionally, psychologically, he's incapable of it because it's shattering to him to feel that he's wrong."