Fox News host Tucker Carlson tore into President Donald Trump for not keeping his campaign promises in a blistering interview with Swiss publication Die Weltwoche.

Hath Hell frozen over?

Carlson, normally a stalwart defender of Trump, told editor Urs Gehriger he is not a fan of the president's boastful behavior.

"I hate that about him," said Carlson. "I hate that… it's not my culture. I didn't grow up like that."

When asked if he thought Trump had kept his campaign promises, Carlson gave an emphatic "no."

Trump's "chief promises were that he would build the wall, de-fund planned parenthood, and repeal Obamacare, and he hasn't done any of those things," Carlson lamented. "There are a lot of reasons for that, but since I finished writing the book, I've come to believe that Trump's role is not as a conventional president who promises to get certain things achieved to the Congress and then does."

Carlson added of Trump:

"I don't think he's capable. I don't think he's capable of sustained focus. I don't think he understands the system. I don't think the Congress is on his side. I don't think his own agencies support him. He's not going to do that."

Continuing Tucker said that "Trump's role is to begin the conversation about what actually matters," noting that the president has achieved very little.

"Not much. Not much," Carlson said of Trump's accomplishments. "Much less than he should have. I've come to believe he's not capable of it."

Well, whaddya know. Perhaps being away from Fox cleared Carlson's head.

As the interview progressed, Carlson blamed Trump for his own presidential shortcomings.

Carlson turning on Trump is a big deal, but his disappointment over Trump's failure to build a border wall and take health care away from people rubbed some people the wrong way.

Others were happy to see Carlson throw Trump under the bus.

Why has Trump not been successful? Carlson blamed the president's lack of understanding about how government functions.

"In order to do it you really have to understand how it works and you have to be very focused on getting it done," Carlson said, "and he knows very little about the legislative process, hasn't learned anything, hasn't and surrounded himself with people that can get it done, hasn't done all the things you need to do so. It's mostly his fault that he hasn't achieved those things. I'm not in charge of Trump."