Those assumptions about electability reflect entrenched biases more than political science, and have a dash of arrogance to boot. An electable candidate, the thinking goes, has to be authentic and broadly appealing. But authenticity itself is coded as white and male when it’s defined by white men.

This perpetual reading of the white working-class tea leaves (or beer hops?) only makes sense if those voters are actually more influential than all the others. In the Democratic Party, they’re not. Just under a third of white men without college degrees said they voted for a Democrat in the 2018 midterms. And Democrats don’t need anywhere near a majority of these men to win. Women vote in larger numbers than men; voters with college and post-graduate degrees turn out in larger shares than those without. These high-turnout groups are the same ones that are trending Democratic. If they're motivated to turn out to vote, a Democrat will wind up in the White House.

But what about those Obama-to-Trump swing voters who will reportedly make or break this election, as they did the last one? The Democratic Party shouldn’t leave anyone behind, but working-class white men are declining as a share of the Democratic base, while whites generally are declining as a share of the general population. The entire premise that white men without college degrees are the only possible swing voters is a faulty one.

There’s also little evidence that most voters pick a candidate based on policies and that a moderate candidate who wrote campaign talking points to appeal to a broad swath of voters would do significantly better than a more visionary and progressive one. Instead of trying to win back a waning electoral and demographic force, Democrats would be better served to consider what will get voters to the polls. Hillary Clinton’s loss can only be explained by a long list of factors, but surely one of them was apathy: The certainty that she had the election in the bag probably depressed voter turnout.

Contrast that to the 2018 midterms, which had a record-setting turnout — and a record number of women elected. Disgust with the Trump administration surely pushed voters to the polls. But so did a slew of exciting candidates who don’t look like the old models of “electable.” They looked a lot more like the people actually electing them.

Women made record numbers of political contributions in 2018 and, at least anecdotally, dominated campaigns behind the scenes. Mr. Trump’s white working-class base still voted Republican, although in lower numbers than when he triumphed. Women of color, and particularly black women, continued their trend of staunchly supporting Democrats, and turnout among racial minorities hit a high at 28 percent of voters, and 38 percent of voters under 30. A majority of white women with college degrees voted for Hillary Clinton in 2016, but it was this group that gave Democratic candidates a new advantage in 2018, increasing its support for Democrats over Republicans by 13 percentage points from two years earlier.

In several key states, including Ohio and Florida, white women with college degrees flipped: A majority voted Republican in 2016 and Democratic in 2018. White men, regardless of education, did not. It’s white women, not working-class white men, who are the most promising swing voters for Democrats in 2020, and who could wind up as loyal lifelong Democrats.