Donald Trump likes to think of himself as a great businessman, but at least one official who served under him says that’s not the case at all.

“Donald Trump is not a great businessman,” former Homeland Security chief of staff Miles Taylor told MeidasTouch. “He is a failed businessman across the board. Trump Steaks and Trump Vodka and Trump Airlines and we could go on and on.”

Taylor also dispensed with the argument that the former president’s wealth is proof of his business acumen.

“Al Capone was incredibly rich,” he said. “You can be rich and not be a great businessman. You can be a fraud. And we’ve seen this with Donald Trump throughout his history. Even people who’ve been huge supporters of his have come away saying, ‘He’s a total fraud.’”

Taylor said Trump took all of his worst tendencies from the world of business with him into the White House.

“And in a lot of ways, he made the U.S. government his largest failed venture yet,” he said, adding that Trump’s “volatility and corrupt nature” made it difficult for government departments and agencies to function.

“I saw it in our own department,” he said, where he was unable to do his job effectively because he was too focused on dealing with Trump’s impulses.

“I had to spend my time focused on how do we manage the president,” he said. “That’s not the sign of a good businessman. He’s clearly not communicating and delegating really well. That’s the sign of the exact opposite.”

He warned business leaders who think Trump might be better for the bottom line that a second Trump term would be so volatile that it would be “dangerous and destabilizing” for the U.S. economy.