Well, with the white working class, Trump not delivering for them won’t win a Democrat votes. The white working class is now a lot like the black working class. One party doesn’t deliver for them and the other is pure poison.
Getting the white working class back into the Democratic fold isn’t something you do with a Presidential candidate selection. Joe Biden is probably the last of that dying breed. Bernie Sanders isn’t really the answer, he may be pro-working class but he can’t win a primary without mobilizing college students and progressives, whose priorities are quite different from working class white voters.
Damon Linker had a great article about where the Democrats go from here and noted that all paths involve risk. Appealing more to white working class voters, something the party can only do through fairly united party effort, risks depressing minority turnout. That’s the nature of adjusting your ideology, you lose voters as well as win voters.