For Christie, it's an example of Trump's penchant for drawing attention with gaudy promises that can't be fulfilled. Another one: Trump's "great line" about building a wall at the U.S.-Mexico border and somehow forcing Mexico to pay for it.
"When you do that, it hurts the credibility of the presidency," Christie said over milkshakes at Lindy's Diner in Keene, N.H., a traditional stop for White House candidates.
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He went on to say that some of Trump's money-making skills in business aren't transferable to government, since presidents cannot simply roll over political adversaries by saying "You're fired."
Christie, who lags in the polls but currently would make the top-10 cutoff for the first GOP debate next week, said the public and media fascination with Trump isn't hurting the party now but would if the outspoken real estate mogul becomes the 2016 Republican candidate.
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"I don't think it would be in the best interests of our party to have someone I don't think would be an effective president as the nominee," he said. "That's why I'm running."