In the run-up to tonight's Democratic presidential debate in Iowa, the last such contest before primary voting begins, one of the big storylines is about who won't be among the half-dozen candidates on stage.

"This debate is so white, it's not allowed to bring the potato salad," cracked Mediaite's Tommy Christopher. "The smallest, whitest one yet," concurred Politico.

With Sen. Cory Booker (D–N.J.) exiting the race Monday, and both Andrew Yang and Rep. Tulsi Gabbard (D–Hawaii) failing to meet the qualification thresholds, the resulting lineup is not just pale, it's ancient—the three highest-polling of the six debaters would each be the oldest president ever sworn into office. A fourth, Tom Steyer, is a hedge fund billionaire who literally bought his way to the podium, after an entire season in which Democrats debated whether billionaires should even exist. (An even older white billionaire, Michael Bloomberg, currently sits fifth in national polls but is not bothering with early primary/caucus states.)

So you can see why the younger, more progressive voices who punch above their weight in Democratic political discourse would be dismayed. "Bad for democracy," pronounced Salon's David Daley. "The system they have designed has suppressed the most loyal base of the Democratic Party," charged Color of Change Executive Director Rashad Robinson in The Washington Post. "Anyone with an understanding of civil rights law understands how the rules can be set up to benefit some communities. The Democratic Party should look at the impact of these rules and question the results."

That is certainly one theory. But I would suggest at least considering another. Cory Booker was one of five Gen X candidates (only one white male among them) who came into the race with ideologically mixed pedigrees—including not a small amount of what progressives would deride as "neoliberal" policy positions on deficits, trade, and education—but then competed with varying levels of believability on being the most woke, before eventually collapsing.

First Sen. Kirsten Gillibrand (D–N.Y.), then Beto O'Rourke, Sen. Kamala Harris (D–Calif.), Julián Castro, and now Booker all made the affirmative choice to either tack heavily left on economics or just downplay their past heresies in favor of talking up issues such as slavery reparations, Medicare for all illegal immigrants, and the racism/sexism of President Donald Trump. The abject failure of this approach is one of the greater underexplored storylines of the 2020 presidential nominating season.

Eleven months ago, this group accounted for about one-quarter of voter support in national polls: Around 12 percent for Harris, 6 percent for O'Rourke, 5 percent for Booker, and 1 percent each for Castro and Gillibrand. Sen. Elizabeth Warren (D–Mass.), who would eventually vault herself up to near-frontrunner status, was then just a face in this crowd: 7 percent. Democrats were making similar murmurs of pride about their energetic and historically diverse field that you heard among Republicans in the first half of 2015.

What happened next? While Warren went on a white-paper spree of policy "plans" for every economic and regulatory issue under the sun, the Gen X Five engaged in more identity-politics emoting than a campus struggle session, only with less sincerity. O'Rourke agonized publicly about his ancestors owning slaves. Harris the cop tried gruesomely to rebrand herself as a hip Jamaican pot smoker. Gillibrand spent valuable debate-stage time talking about the need to educate people about her white privilege. Booker pushed for reparations and policed Joe Biden's language, while Castro was busy shaking his damn head that all these leftward lurches didn't go nearly left enough.

The late-night comedy skits wrote themselves. And by August, Warren was outpolling all five whippersnappers combined.

It's not that the more successful septuagenarian progressives shied away from calling Trump a racist—far from it. But voters did not have to guess about what got the northeastern senators up early every morning: It's the economic policy, stupid. What, exactly, was Kirsten Gillibrand's selling proposition? Why were O'Rourke and Booker (at least until the last of the latter's debates) running away from much of the stuff that made them interesting in the first place?

What makes their choice that much more curious is the persistent math of this race: The progressive bloc in the 2020 Democratic field has consistently lagged the centrists by about 10 percentage points. The RealClearPolitics running national averages for Biden (27.4 percent), Pete Buttigieg (7.8 percent), Bloomberg (6.2), and Sen. Amy Klobuchar (3.0) (D–Minn.) combine for 44.4 percent; Sanders (18.8 percent) + Warren (16.8) + Steyer (2.2) = 37.8. Instead of using their ideological dexterity to compete against a very old-looking frontrunner for the scared-of-socialists vote, the Gen Xers chased whatever progressive crumbs hadn't already been hoovered by two strong candidates.

The great irony of this blown strategy playing out even today is that Elizabeth Warren, after benefiting directly from her competitors' stumbles, seems to be making the exact same tactical mistake. By leaking a private conversation with Sanders in a not-particularly-convincing attempt to make him look possibly sexist, Warren's campaign is engaging in the same kind of bad-faith word-policing that so many voters find off-putting. Tonight's debate may well feature several minutes of linguistic hair-splitting and I'm-not-saying/I'm-just saying in place of conversations about what the federal government should and shouldn't do. That is not what got Warren into the top three.

Donald Trump, like successful populists worldwide, campaigned and won in part by railing against the perceived political correctness of the country's political, journalistic, and cultural elites. Continuing to mash that button is one way he strengthens his grip on the Republican Party, though there's some evidence that the attendant crude manners and cruel policies are driving away suburban voters, especially women.

Democrats and other Trump-averse political actors thus face a challenge: How to forcefully oppose the president's malodorous actions without alienating fence-sitters via in-group jargon and out-group condescension? The now-vanished field of Gen X candidates already tried out I-am-Spartacus histrionics, serial F-bombery, and even a bizarre if fleeting attempt to make school busing a litmus test. Forget the general election; none of this worked in the Democratic primary.

How Democrats react to #DebatesSoWhite might give us a hint of how they're approaching the Trump problem. Black voters have overwhelmingly preferred Joe Biden; Bernie Sanders has drawn strong Latino support. Those who pin such preferences onto structural racism are wandering directly into the briar patch of false consciousness, which is rarely a good look.

In a season where electability is the primary Democratic virtue, Democratic voters have been sending a consistent message: Identity politics ain't the ticket. Maybe next time around the Gen X candidates of all hues and genders will run as how they really are, as opposed to how Brooklyn Twitter wants them to be.