Donald Trump, the face of birtherism as we know it, has lately begun to single out Ted Cruz over his status as a "natural-born citizen." Nevermind that no serious pundit or politician is really raising these concerns. Nevermind that Ted Cruz's eligibility to be in this race is not actually in question. Donald Trump is going to make an issue of this, because Donald Trump is a businessman, and businessmen know threats to their market when they see them.
Not content with the scalps of Scott Walker, Jeb Bush, Rick Perry, Bobby Jindal, and others, Trump has to go after Cruz. If he is so concerned with Cruz's standings in Iowa, he must not really believe that 11-point lead after all.
It's time for Donald Trump to either settle his problem with the FACT that he was a Democrat and supported Democrats, or get out of the race.