This will be his biggest challenge. Not winning women or minorities, etc over, but convincing status quo Democrats to come along as well. Class has come up more than once and some Democrats are quite well off and are nervous that they're going to have their money liquidated and given to people in trailer parks or something. Sanders is going to have to convince those people that fixing healthcare doesn't mean millionaries will be outlawed or that reducing student debt is about "punishing" success.