The football term is "Prevent Defense". He's the frontrunner -- just don't screw it up. The only time he was "Trump" was when one of the others came close to landing a power punch. Then, he unleashed his Trumpiness and slapped it back down.
The little jabs, he didn't much care about, but he made sure no one hit him hard.
Unfortunately, I don't think that strategy necessarily plays to undecideds. Trump may have declared himself the winner too soon.
Trump may have declared himself the winner too soon.
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We have a long way to go before election day. Remember that Hillary and Giuliani were in the lead in September of 2007.