Trump tweeted that Dimon “doesn’t have the aptitude or ‘smarts'” to be president, adding that he’s “a poor public speaker & nervous mess.”

At a New York event Wednesday morning, Dimon had claimed he could beat Trump in a presidential election, “because I’m as tough as he is, I’m smarter than he is.”

Later that day, Dimon walked back his unscripted comments, CNN Money reports.

“I should not have said it,” Dimon wrote in the statement. “I’m not running for President. Proves I wouldn’t make a good politician. I get frustrated because I want all sides to come together to help solve big problems.”

Still, Trump—never one to let a negative comment slide by, as per his advice in his 1987 memoir, The Art of the Deal—clapped back at Dimon, saying it’s his “great economic policy” that makes bankers like Dimon look “much smarter than they are.”

The problem with banker Jamie Dimon running for President is that he doesn’t have the aptitude or “smarts” & is a poor public speaker & nervous mess – otherwise he is wonderful. I’ve made a lot of bankers, and others, look much smarter than they are with my great economic policy!

— Donald J. Trump (@realDonaldTrump) September 13, 2018

Trump has historically been complimentary of Dimon: In 2012, Trump tweeted that Dimon “is a good guy and a great banker.” After the election in 2016, Trump offered Dimon a position as Treasury Secretary, which Dimon turned down.

Even after criticizing Dimon’s presidential potential in Thursday’s tweet, Trump wrote, “otherwise he is wonderful.”

According to Bloomberg, JP Morgan said it has no further response to the president’s comments.