House 2016: The Balancing Act: How expectations of a Clinton victory could hinder Democrats down-ballot By Kyle Kondik
While Hillary Clinton still leads Donald Trump in most national polling, her margin is not what it once was: She’s up about five points in the HuffPost Pollster average, down from nine points in mid-April, and she’s up just two points in the RealClearPolitics average, also down from nine points seven weeks ago. Now that she’s the presumptive nominee, Clinton will hope to restore those numbers to their prior luster.