His rise has been on the backs of his message of economic populism and restoring inequality. He benefits over Clinton, and even Biden if he gets in, as being the outsider and fresh face, even at age 74. But if the conversation in the Democratic primary turns to renewed pushes for sweeping gun control measures, it's bad news for Sanders. He's going to have to explain every time he voted against some very popular restrictions, and so far in major interviews, he has not proven very adept at doing so.