The idea that a Democratic Trump could ever win the nomination or be a major factor is silly and based on the absurd premise that the two parties are mirror images of each other and function basically identically aside from ideology. You could never have a Democratic Trump because Trump's campaign is based around demonizing and attacking large groups of people. You can't do that as a Democrat and be successful because those people are going to be represented in the Democratic Party at some level no matter who they are.
Like take the most obvious example: Evangelical Christians. So what if some candidate ran a campaign bashing them like Trump does immigrants or Muslims? Well over 25% of evangelicals vote Democratic. There are tons of them in the Democratic Party and if someone wants to point out that they are largely or possibly even majority black and Hispanic...yeah how do you think that would look? It would go nowhere. Gun owners? Duh. There's tons of gun owning Democrats. And so on.
I think a Democratic Trump could win the nomination, they just have to run on the same political platform like Bernie Sanders, but add in some controversial statement making stuff about White Evangelical Christians. I can say I know a lot of gun owning Democrats (I live in TX so this may be a factor), but I have yet to meet a White Evangelical Democrat.
