I simply can't get over how so many liberals want to openly reject white, working class voters. Can you imagine the reaction if they wanted to reject any other demographic?
Let's look at some headlines first.

“There’s always been something problematic about the Democratic Party’s fixation on white working-class voters,” writes Sally Kohn at the Daily Beast. “After Alabama, it’s clear that obsession isn’t just fraught with bias. It’s also dumb.”

Steve Phillips of Democracy in Color remarked in a New York Times op-ed: “The country is under conservative assault because Democrats mistakenly sought support from conservative white working-class voters susceptible to racially charged appeals. Replicating that strategy would be another catastrophic blunder.”

The Obsession With White Voters Could Cost Democrats the Virginia Governor’s Race

In my book, Brown Is the New White, I titled one of the chapters “Blinded by the White” to bring attention to the reality that “much of the progressive movement and many progressive campaigns are still dominated by White leadership, fixated on White voters.” Since the last presidential election, this pattern has continued unabated with nearly all progressive attention focused on the white working-class voters who supported Trump in large numbers.

Sanders: ‘We Don’t Need White People Leading the Democratic Party Right Now’
Why Are Democrats Pandering to White Voters?

So it's OK to pander to minorities, but not to poor whites?

The message here is clear and unmistakable: It's bad to care about the white working class.

Why?
Without openly admitting racial prejudice, why is it bad to care about the obviously struggling white working class?
I'm at a loss to come up with a reason for this prejudice that isn't based on either racism or classism.
Which makes it totally bizarre that liberals that wrap their prejudice in a sort of morality. When did prejudice become moral?

But let's not get hung up on that right now.
I want to focus on basic math, the traditional enemy of ideologues.
Liberal Democrats are just as bad as Republicans when it comes to simple math, otherwise they would never expect to win elections while at the same time reject whites.

Nearly 3/4 of the population of America is white, and they think you can win elections without them? Are they insane or just stupid?
There is no realistic scenario where this works.
[note: the census doesn't separate Hispanics, which are about 16% of the population]

So if you want to know why Democrats have been destroyed at every level of government, look no further than a very vocal, openly prejudiced minority that can't do math.

Now let's look at the deplorables factor.
The assumption by many liberal democrats is that the white working class is hopeless. Besides the fact that you can't make such a broad assumption about any demographic without relying on either racism or classism, it also isn't true.
Let's go back to the math.

In 2012, Obama lost whites without a college degree nationally by 25 points. Four years later, Clinton did 6 points worse, losing these voters by 31 points, with shifts against her in Rust Belt states generally double or more the national average.

Had Clinton hit the thresholds of support within this group that Obama did, she would have carried, with robust margins, the states of Michigan, Wisconsin, Pennsylvania, and Iowa, as well as (with narrower margins) Florida and Ohio. In fact, if Clinton could simply have reduced the shift toward Donald Trump among these voters by one-quarter, she would have won.

To put this into fuller context: If Clinton had replicated the black turnout levels enjoyed by Obama in 2012, she still would have lost the 2016 election, because the other shifts against her were so powerful.

Put another way: No, motivating the AA-community would not have won Hillary the election.
Not rejecting white, working class voters, simply to 2012 levels, would have been enough.

The Daily Beast’s Kohn and others argue that heavy black turnout and support led to Jones’s victory — period. But Jones’s triumph was not attributable to his strong showing among black voters alone, or even a combination of black voters and white college graduates. My analysis indicates that Jones benefited from a margin swing of more than 30 points among white non-college voters, relative to the 2016 presidential race in the state.
The swing toward Jones was for sure even larger among white college graduates. But without the hefty swing among the white non-college population, particularly women, there is no way Jones would have the state, or even come close.

Alabama would have elected a pedophile to the Senate, no matter what the AA-community did, if not for a drastic swing in the white, working class vote. That's not the story you hear on TOP.

Finally, there is Chuck Shumer's famous line about how he wants to dump the white working class for Republican suburban voters. He's not good with math either.

white non-college voters remain a larger group than white college voters in almost all states — and are far larger in the Rust Belt states that gave the Democrats so much trouble in 2016: Iowa is 62 percent white non-college versus 31 percent white college; Michigan is 54 percent white non-college versus 28 percent white college; Ohio splits 55 percent to 29 percent; Pennsylvania 51 percent to 31 percent; and Wisconsin 58 percent to 32 percent.

Ohio, where Democrats’ white non-college deficit roughly doubled from 16 to 31 points in 2016, is a good example of the challenges Democrats face. Given this deficit, Democrats could completely replicate, in 2020, Obama’s high-water performance among black voters and still lose the state handily, probably by around 5 points. There is no way around it — if Democrats hope to be competitive in Ohio and similar states in 2020, they must do the hard thing: find a way to reach hearts and minds among white non-college voters.

It really isn't hard to win back a significant percentage of the white working class.
Any demographic that is obviously struggling and doesn't feel it is being represented is ripe for the taking.
Of course the Dems have to want to do it, and that is an open question.