If you look at past polling, we've reached the stage of the year where past presidential primary winners had largely already been identified. On Feb. 17, 2004, John Kerry held a huge lead among Democrats that he'd keep. In 2008, Barack Obama and John McCain each led his party on this day, and would keep on leading until their conventions. The year 2012 is the only exception, with Rick Santorum having seized the GOP lead from Mitt Romney -- and Romney seizing it back two weeks later, for good.
In each of those years, we had more primary elections under our belts than we do now, but, with the exception of the 2008 Democrats, we also had less stability. Donald Trump will have led in Real Clear Politics' polling average nationally, save a day or two when he was tied with Ben Carson, for prec...
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