Ron DeSantis and Chris Christie ripped Donald Trump for skipping the second debate. He was "missing in action," DeSantis said. Christie labeled him "Donald Duck," which fell about as flat as you might expect.

But if neither jab was likely to put a scratch on the frontrunner, what they did reveal was something more significant: the tacit recognition by Trump's rivals that his absence from the debate stage is damaging them, relegating their primary debates to a series of confrontations at the "kiddie table."

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