If there is one rule of politics that still stands, it’s that it never pays for a candidate to punch down. Trump established this with his attacks on Judge Curiel and the Khan family that backfired badly. But here we are, a solid month into the pivot, a little over a month before the election, and he has allowed himself to get lured into attacking a Latina former Miss Universe — for her weight! The Clinton campaign set this up perfectly, with Hillary putting it into the water last night and a web video and conference call with Alicia Machado ready to go. This isn’t a Khan-level event, but it is really stupid of Trump to take this bait (he went after Machado on TV this morning). I expect Kellyanne and Co. are trying to reel him in as we speak.