About 3million hardcore Clinton supporters in 2008 voted for McCain and then stayed with Romney. They returned to Hilary in 2016 but Black Americans didnt turn out for her in large numbers and 3million white blue collar Obama supporters switched to Trump.I didn't think he'd be nominated, never mind be elected but I couldn't believe the hatred of Clinton among some rational people I know. I think that the only way Trump will be elected is if the Democrats select a radical as nominee or VP candidate. Negative campaigning is very powerful.
If Sanders is selected those 3million Hilary supporters who went with McCain/Romney are likely to back Trump. Bernie would take back some of Trumps Obama voters. So it'd even out. But if Bernie's class narrative resonated that poor/struggling Americans nomatter of what colour/creed are being victimised/targeted by a system rigged to enhance elite privilege than Trump could be routed across the rust belt. The DNC/CNN/NYT and their corporatist buddies of course would be apoplexic Sanders winning on an equality/redisributive economic agenda that unites the struggling masses, so of course they non stop promogate 'white supremacy' with the aim the mininum wage mechanic in West Virginia never can find commonality with the single mum Latina barista from San Bernadino. Truth be told the corporatist agenda would consider stoking a race war as preferable to the US embracing genuine leftist economics.