I have stated several times on this blog that Bernie Sanders is not a Democrat. He may be running in the Democratic primary (and caucuses with Senate Democrats), but he shuns the party label -- and always has. He has yet to say in this campaign -- "I am a Democrat", and I doubt you'll ever hear him say that.
So, why is he running in the Democratic primary? He's just using the Democratic Party apparatus for his own political ends -- and he doesn't really try to hide that. Consider these posts from Politico.com:
March 1, 2016
The biggest argument was over running as a Democrat. Over and over, Bernie Sanders said he didn’t want to. He’d spent his whole life purposefully outside the Democratic Party. He treasured his status as the longest-serving independent in Congress. Running as a Democrat wasn’t who he was. He didn’t want to do it that way.
His longtime consultant Tad Devine and the rest of the group came down hard: this is never going to have a chance of working unless you get over it. Suck it up, they told him.
March 14, 2016
Bernie Sanders on Monday told NBC’s Chuck Todd that he ran as a Democrat to get more media coverage.
During a town hall-style event in Columbus, Ohio, the independent Vermont senator said, “In terms of media coverage, you have to run within the Democratic Party.” He then took a dig at MNSBC, telling Todd, the network “would not have me on his program” if he ran as an independent.
Money also played a role in his decision to run as a Democrat, Sanders added. “To run as an independent, you need — you could be a billionaire," he said. "If you're a billionaire, you can do that. I'm not a billionaire. So the structure of American politics today is such that I thought the right ethic was to run within the Democratic Party.”Bernie Sanders wanted to make a political statement, and he knew he could not do that as an Independent Socialist (which is what he really is) -- so he decided to use the Democratic Party. He is not now, and never has been, a Democrat -- and when he runs for the Senate a couple of years from now, he'll once again run as an Independent Socialist (not a Democrat).
This is a major reason why he will not get the Democratic nomination for president. Democrats know he is not one of them -- and they will nominate Hillary Clinton (who has a long and proud history of being a Democrat, and supporting Democratic issues and causes).