Donald Trump has frequently turned to name calling during his campaign, but at Tuesday’s GOP presidential primary debate Jeb Bush turned the tables by dubbing him the “chaos candidate.”

“He’s the chaos candidate, and he’d be the chaos president,” Bush said at the CNN debate in Las Vegas.

Bush, who is polling in single digits and has sparred in previous debates with the front-running Trump, seemed reluctant at first to re-engage Trump, saying, “OK, he said it first.”

Trump has referred to Bush as “low energy,” called others “dummy” or “stupid” and most recently called fellow primary contender Texas Sen. Ted Cruz, whom several polls now show leading in Iowa, “a bit of a maniac.”

Trump, a billionaire real estate mogul and first-time candidate, responded to Bush’s dig Tuesday by suggesting he said it only to try to jumpstart his sagging candidacy.

“He doesn’t believe that,” Trump said. “He’s failed in his campaign.”

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