The DNC is terrified of Bernie getting the nomination because they think he can't beat Trump. I say vote for him anyway because none of the other candidates can beat the beast either. If Trumpoid Boris can win in a landslide, the real bad-hair monstrosity will win as well. British politics always was the canary in the coalmine for the US. First Thatcher then Reagan; first Brexit then Trump.
The current group of Dem candidates are 5 septuagenarians and Mayor Pete. The only problem with Pete is that he will never inspire black voters to get out to the polls because of several issues during his term as mayor of South Bend, IN: firing the black chief-of-police; a police force that is made up of a much lower % of minority officers than the population; an urban renewal project where most of the houses that were brought up to code were in white neighborhoods and most of the ones razed were in black neighborhoods and just as he began his candidacy a black man shot by a white cop whose body cam had been turned off. Dems can't win the presidency without the black vote in full force: If Hillary would have gotten even half of the minority voters as Obama did, Trump would have been relegated to the dustbin of history 4 years back. I don't understand why some viable candidates like Booker, O'Rourke and Harris couldn't gain any traction, but we're left with what we have, and none will beat Trump.   
The silver lining is that because of the perverse nature of American politics the feckless Republicans will lose the Senate, the Dems will hold the house and the Donald, grandson of an illegal immigrant brothel keeper, son of a klansman, will just have to order a big box of veto pens.