John McCain Thinks Donald Trump Might Apologize About Those POW Comments. McCain Doesn't Understand Trump's Brand.

John McCain is the latest elder statesman in the Republican Party withhold his support from the party's presidential nominee. In an interview Sunday, McCain said that he won't support Donald Trump until Trump retracts disparaging comments he made about about prisoners of war, and McCain himself, over the summer. That's a reasonable demand, but let's be clear about this: The odds of Trump apologizing to McCain for his POW comments are as high as the odds of Trump growing wings and flying away.

Trump offended quite a few people in July when he denied that McCain, who spent five and a half years in a Vietnamese prison camp, was a war hero.

"He's not a war hero," Trump said. "He's a war hero because he was captured. I like people that weren't captured, okay?"

On Sunday, McCain said that he wasn't yet ready to support Trump, but that he might be willing to if Trump took back those comments.

"I'd like to see him retract that statement. Not about me, but about the others," McCain said on CNN's State of the Union. "I think it's important for Donald Trump to express his appreciation for veterans, not John McCain, but veterans who were incarcerated as prisoners of war."

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I'm a bit surprised McCain is even entertaining the notion of endorsing Trump, but no matter: It's not going to happen, because Trump will not be retracting those comments. Here's the thing about Trump: While he sometimes makes policy recommendations and then walks them back — like he did recently with his insane comments about the U.S. debt — he never, ever, ever takes back his insults and put-downs.

When you think about it, this makes perfect logical sense. Trump's appeal, to the extent that he has appeal, isn't based on his policy views or political ideology. It's built almost entirely on the force of his personality, and a huge component of Trump's personality is that he never backs down from political incorrectness in the face of critics.

Can you think of the last time Trump apologized, retracted or expressed regret for saying or doing something offensive. It almost never happens. He didn't apologize for referring to Mexican immigrants as "rapists," or for calling black people lazy, or for insinuating the Megyn Kelly was on her period during that Fox News debate, or for calling Rosie O'Donnell a "disgusting pig," or for claiming that Muslims in New Jersey celebrated the attacks of Sept. 11, or for any number of gross things he's said over the years.

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Trump is happy to occasionally backtracking on policy matters, because this poses no threat to the Trump brand. But apologizing for being offensive goes directly against the brand Trump has carefully built for himself. If he were to retract the comment he made about McCain, he might win over the Arizona senator. But in exchange, he'd probably alienate a huge portion of his base, which would be outraged that almighty Donald was caving to the demands of politically-correct elites in Washington.

This is a perfect microcosm of the larger issue Trump will have if he tries to moderate his tone, or pivot to the center, during the general election. His entire candidacy is built on the fact that he doesn't hold back, doesn't pull punches, and isn't afraid to be offensive. The moment that he starts taking back statements because they hurt somebody's feelings is the moment he ceases to be Donald Trump — and if Trump has made anything clear in this campaign, it's that he can't possibly be anybody but himself.