It's something Trump has done before. In a 1990 CNN interview reviewed by CNN's KFile, Trump walked off an interview when reporter Charles Feldman pressed him on questions over the financial stability of his Atlantic City casinos. The interview took place in March 1990, just days before Trump's billion dollar Atlantic City casino, the Trump Taj Mahal, was set to open.

"When they go low," Clinton says on the campaign trail, "We go high," her supporters shout back. In 2008 and 2012, President Barack Obama's campaign aides anointed Michelle Obama "The Closer." This year, Hillary Clinton may well designate her most popular surrogate the starter, the reliever and the pinch-hitter, too.