John McCain was not at his most prudent when he recently said of Fidel Castro: “I hope he has the opportunity to meet Karl Marx very soon.” The funny line is, in its way, a welcome change from the mild reverence that’s attended the dictator’s retirement. But in wishing Fidel Castro a speedy trip to hell, McCain is begging critics to accuse him of being unreasonable, hot-headed, and generally too ill-tempered to serve as president.

With Fidel gone, it is at least conceivable that the next U.S. president will be called upon to step up U.S.-Cuban diplomacy. It’s not hard to imagine the chill that McCain’s words might cast on a face-to-face-meeting between himself and Fidel’s brother and successor Raul. To make matters colder still, McCain also said, “Apparently [Fidel] is trying to groom his brother Raul. Raul is worse in many respects than Fidel was.”

McCain’s lucky in a few respects here. The statements are not that easy for American politicians to criticize. Neither Barack Obama nor Hillary Clinton need to go on record as defending Fidel or Raul Castro. This could keep their lips buttoned. And Mike Huckabee, whose campaign just may be far enough out there to hint at some kind of defense of Raul, has fallen off the radar. No matter what, this is a reminder that McCain’s anti-talent for sound-bites remains his biggest liability.