Oy. If nothing else, Bernie is an independent. The Democrats are not his party. They are his natural allies, or should be, and he understood U.S. elections well enough to know that if he ran as a third-party independent he and the Democrats would both lose, electing their natural antagonist: whichever Republican. So, in sum, Bernie ran in the Democratic primary to be the Democratic candidate, but he was not and is not a Democrat.