Former Vermont Governor Howard Dean said President Donald Trump is “mentally incapacitated” during an MSNBC segment on the shutdown battle over border wall funding.

“As I said before, I actually think the president is mentally incapacitated, and I have thought so for quite some time,” Dean said on MSNBC Sunday. “He says things that he knows aren’t true, I suspect, and that somehow he thinks people are going to believe, and they just don’t.”

“So essentially you can’t really make a bargain with somebody who is irrational, because they won’t keep it — Republicans have been quoted off the record as saying such a thing,” Dean continued. “Republicans and the Democrats in Congress have got to do the best they can to run this country in the absence of a chief executive who is really a chief executive.”

Later on in the segment, Dean said Trump’s “own staff is terrified of what’s happening here.” Dean said.

“This guy is a completely irrational person,” he added, before explaining why Trump will ultimately get the blame for this shutdown: “Here’s the fascinating thing about this, because Trump put his finger on it when the government shut down before he was in office. The president always gets the blame. If the stock market tanks, which it will at some point if this goes on for any length of time, Trump is going to get the blame. Whether it’s his fault or not.”

“That’s what happens in politics, the top guy always gets the blame. He’s going to have to figure out a way out of this. The longer it goes on, the more problems for Donald Trump,” he said.

Watch above, via MSNBC.