Forty-eight hours ago, the campaign of Sen. Marco Rubio (R-Fla.) and the super PACs that supported him had apparently found a cohesive, potent attack on Donald Trump -- that the mogul was a "con artist" who defrauded "the little guy." Any attempt to cohere around an anti-Trump message is gone. For the past 24 hours, Rubio and surrogates have eviscerated Trump for a rambling non-response to a question about endorsements from white supremacists. And for just the last hour, Rubio allies and Sen. Ted Cruz (R-Tex.) have demanded answers from Trump on BuzzFeed's report that the candidate had more immigration...