Investigative journalist and Trump expert explains just how little Trump actually knows about the Constitution

Pulitzer Prize-winning investigative journalist David Cay Johnston got to know President Donald Trump as a business and economics reporter in New York. He’s now become the definitive expert and biographer on the truth behind the Republican leader.

During a CNN panel discussion about Brett Kavanaugh's approval being nearly the lowest ever, Johnston rejected the idea that Trump picked Kavanaugh to get him out of trouble. But not for the reason one might think.

"He did that because the people advising him told him that," Johnston said. "Donald doesn't know anything about the Constitution. I mean just look at the interview on Fox he said there is something about high crimes in the Constitution. He listened to advisors that if he was looking for protection and refuge as things go forward with the [Robert] Mueller investigation, there is the kind of guy you want to have on the supreme court."

Johnston said that he believes Democrats should be asking Kavanaugh whether he intends to recuse himself from any decision that comes out of the Russia investigation.

During a conversation about Andrew Gillum and the racism he faced from the GOP, Johnston explained how the president has taken over the Republican Party and turned it into "the cult of Trump."

"It is very troubling to see Republicans, who in private, will say that they're very uncomfortable with Trump's racism and ignorance and a number of other things, refuse to stand up to him because they fear they will be voted out in Republican primaries," he continued.

He went on to say that his father was a World War II veteran, who gave his life to his country and "he never felt that he did anything other than sacrifice for the welfare of his country." Johnston said that if the GOP is more concerned about losing an election than doing the right thing, "shame on you."

Watch the full conversation below: