Sanders has already left the Democrat Party. (I can't bring myself to call it democratic considering the super-delegates.) Read the comments in the following article. (Link here.) The liberals are angry. Sanders supporters are not going to flock to Hillary--Bernie's speech was like that of a hostage with a gun to his head in an ISIS video. It fooled no one.
I hope Bernie runs. I disagree with him on everything, but he's sincere. You can't say that about Hillary Clinton.