Can't be both a democratic socialist and an FDR liberal Democrat unless one believes in four myths:
1. Sanders is a "democratic socialist," not an actual socialist.
2. "Democratic socialism" means all the best programs and proposals of the Democratic heroes.
3. FDR and LBJ were democratic socialists.
4. Bernie has Democratic roots, not socialist roots.
"There are two major lanes on the liberal side of politics: the socialism-not-capitalism lane and the capitalism-not-socialism lane. I'll call them the socialist lane and the FDR liberal lane. Essentially everyone has been clear on the difference until now ... . ... Sanders pretends the socialist lane simply does not exist by never mentioning any of it except for democratic socialism which he incorrectly moves into FDR's lane. In fact, he no longer openly advocates any socialist ideas, but instead claims FDR's ideas are democratic socialism. Finally, he removes the word 'liberal' from from FDR's lane, even though FDR spent spent his presidency establishing it as his brand.
"Both factions support FDR's Second Bill of Rights. ... FDR is basically the Democrats' patron saint and they have been implementing parts of the Second Bill of Rights whenever they got the chance, right down to Obamacare in 2010. ... However, [Bernie supporters] see that Democrats reject socialism/democratic socialism and conclude (falsely) that they are rejecting FDR's Second Bill of Rights. Then they conclude that non-socialist Democrats are shills for Wall Street or throwbacks to 'neoliberalism' ... . The polarization of his followers is good, even life saving, for Sanders. Otherwise, everyone would see he is in the socialist lane that's never gone anywhere. But it is devastating for the Democratic Party, which, of course, means it's good for Trump."
Steven Stoft "Ripped Apart: How Democrats Can Fight Polarization to Win"