Trump's obsessed with John McCain because 'he wants to be him': Presidential historian
Sen. John McCain (R), Donald Trump -- AFP/Gage Skidmore via Flickr

Presidential historian Mark Updegrove noted President Donald Trump likely wants to "be" Sen. John McCain (R-AZ), and that's why he tends to go on the attack more frequently.

"The thing is that John McCain is everything I think Donald Trump wants to be," Updegrove said. "He’s a bonafide American hero, and he had the respect of people worldwide, and I think Donald Trump doesn’t realize what most bullies don’t realize: You don’t build yourself up by tearing someone else down. I think Donald Trump is constitutionally incapable of putting his ego aside and while he mocks what being presidential is all about, being presidential is, I think, primarily about restraint and knowing how to put the office above one’s self and not stoop to petty politics."

He also noted he's concerned that the White House staff feels like they have to appear on cable news to save Trump while he tweets about meaningless drivel.

"Actions speak louder than words, and Donald Trump has yet to condemn these attacks in a way that’s credible and denying that white supremacy is not on the rise is to deny what’s been happening in the world," Updegrove said. "So I think, it’s deeply concerning for our president not to come out more unambiguously around the subject of white supremacy."

Trump did send out a tweet sending "best wishes" to the families of the 50 people killed in the New Zealand terrorist attack.

Watch the interview below: