Donald Trump won the Republican nomination through the "power of not being a politician," and his slogan, "Make America Great Again," means different things to different people who all feel like they've been left behind economically, said Nathan Gonzales, editor and publisher of The Rothenberg & Gonzales Political Report.

"Some people thought it meant build a wall, some thought it meant better trade deals, but everyone sort of projected onto Trump whatever they wanted," Gonzales said at the IRI Vision Annual Conference on Monday.

He still believes Clinton can win, even though her post-convention lead has "almost entirely evaporated," because she only need to win one of four key states—Ohio, Virginia, Florida or Colorado—while Trump needs to win all four.