David Cay Johnston, the author, tax expert and journalist who covered Trump for decades, doesn't pull any punches as he tells Joy Reid just how bad Trump is.
She asked what makes him act the way he does, since the White House physician ruled out cognitive problems.
"I want to challenge what the Navy doctor said," Johnston said.
"You can go online and take that test. I took it. It's a snap. Of course, if you looked at the test ahead of time, it would be a snap. It's a test for predementia and dementia, not all the other problems Donald has in his head. The greatest advisers in the world reside there, remember. He is the problem here.
"Mitch McConnell said, 'what does he want?' Donald Trump sold himself as the great negotiator. 'We're going to win. We're going to win. We're going to win so much, you'll say please, Mr. President, no more winning.' He can't even make a budget deal. He's a con artist. He's a fraud. He doesn't know what he's doing. The faster we come to recognize that, the more we can move on."
"So this is Donald Trump on Friday. He keeps trying to sell the idea that he's already a successful president, already better than Barack Obama. This is him doing that on Friday," Reid said.
TRUMP: Our country is doing really well. Our economy is perhaps the best it's ever been. You look at the job numbers, you look at the companies pouring back into our country, you look at the stock market at an all-time high. Unemployment, 17-year low.
"So the economy is not appreciably different than it was when Barack Obama was president. Do you think Donald Trump believes these things? Is he being fed this by people around him who feel this?" Reid asked.
"Donald Trump is a salesman, like all con artists, he sells you what he wants you to hear," Johnston said.
"Job growth is down 20%, which is what you would expect at this stage of economic growth which began near the beginning of the Obama administration. Tax revenues will temporarily be up only because we gave enormous discounts to these corporations to bring back profits they siphoned out of the U.S. as zero interest loans from our government.
"Many of the companies that announced they're giving raises to people started laying other people off. The economy is doing well. I wouldn't dispute that for a minute. It's not because of Donald Trump. At the same time, what I show in my book is that he has let loose political termites into our government and they will damage the economy, put your health at risk and especially your children, if your my age, your grandchildren's health.
"That's what we need to focus on, not so much his crazy behavior."