Six months ago, I wrote:
Trump's biggest mistake during the primary was to feud with people who were not running against him...Clinton can exploit Trump's propensity to retaliate against anyone who crosses him by deploying surrogates to batter him with a fusillade of insults. If Trump were smart, he would ignore them and focus on Clinton, but his reaction to Elizabeth Warren's tweets suggests he cannot resist the urge to counterpunch, even when it doesn't serve his interests. With every over-the-top smackdown, he will distract voters from his message and deflate whatever presidential gravitas he manages to muster.
Since then, we have seen this scenario play out repeatedly, most remarkably in the case of Trump's feud with the parents of Humayun Khan.
Now it's happening again, and I believe that this feud with former Ms. Universe Alicia Machado will finally spell the end of his campaign.