A little more than halfway through Tuesday night’s Democratic debate, the politics-of-normalcy candidate, warning voters against the dangers of ambitious plans, gave Massachusetts Sen. Elizabeth Warren the opening she needed.

“I think Democrats win,” the moderate said, “when we run on real solutions, not impossible promises; when we run on things that are workable, not fairy-tale economics.”

An eager-looking Warren had her hand raised for a response.

“You know,” she said, “I don’t understand why anybody goes through all the trouble of running for president of the United States just to talk about what we really can’t do and shouldn’t fight for.”

All John Delaney could do was grin until the laughter subsided.

John Delaney? Yes, the moderate on whom Warren spent this executioner’s bullet was the former representative of Maryland’s 6th Congressional District, John Delaney, currently polling at nothing and trending nowhere. It wasn’t Joe Biden, the moderate whom she would need to beat, because of the Democratic National Committee’s decision to split the loaded presidential field by random draw (the mechanical act of which CNN, this debate’s sponsor, also recognized it could sell ads against.)

The two-night setup left Warren and her fellow top-tier candidate at the left end of the spectrum, Sen. Bernie Sanders, with no opportunity to debate the only viable manifestation of centrism in the race. Instead, they spent the night fending off a platoon of mini-Bidens.

Delaney, judging by airtime, appeared to be CNN’s preferred mini-Biden. But the network also served up Montana Gov. Steve Bullock, Ohio Rep. Tim Ryan, and Colorado Gov. John Hickenlooper to perform the same television-drama function as pragmatic foils to the lunatics Sanders and Warren. Each had marginal differences in emphasis that, when assembled, created the effect of a Biden Voltron: Delaney was the “business solutions” Biden proxy, Ryan the “heartland” one, Bullock the “pragmatism wins red states” one, and Hickenlooper … John Hickenlooper was on the stage.

Sign Up for the Surge Keep up with the race for 2020 with Slate’s weekly presidential campaign newsletter, written by Jim Newell. We encountered an issue signing you up. Please try again. Please enable javascript to use form. Email address: Send me updates about Slate special offers. By signing up, you agree to our Privacy Policy and Terms Sign Up Thanks for signing up! You can manage your newsletter subscriptions at any time.

Especially in the first hour of the debate, the moderators just read critiques of left-wing policy ideas like single-payer health insurance or the decriminalization of unauthorized entry into the country, asked Warren and Sanders to defend them, and encouraged the mini-Bidens to sic ’em.

Ryan criticized Sanders for the backlash his single-payer health care bill would create among union members who’ve negotiated strong health plans of their own. Bullock went after Warren for her plan to decriminalize illegal entry, saying that the law didn’t need to be changed, just the occupant of the Oval Office. Bullock also criticized Sanders, and other unnamed “Democrats” for sounding like they were “part of the problem” when they would go after fossil fuel industries.

[Support Slate’s 2020 coverage. Join Slate Plus.]

These are all—well, some—worthwhile topics to debate. How well Warren and Sanders responded to these charges likely depended on where you, the theoretical viewer, rested on the political spectrum. If you believe that Democrats need to be bolder and more aggressive in their visions for the country, you probably thought that Warren and Sanders got the best of them; if you think those visions are either impossible to achieve or too far left to defeat Donald Trump, you probably sided with the Biden proxies.

Wherever you landed, though, wouldn’t it have been more useful—and less time-consuming than watching a total of six hours of debate across two nights—to have watched Warren and Sanders have out their differences with Joe Biden himself? To see the candidate who’s earned one-third of the party’s support in a 20-odd-way race debate Elizabeth Warren and Bernie Sanders on health care, immigration, climate change, tax policy, anything? It’s not as if John Delaney is going to surpass Joe Biden by doing a stellar impression of him.

Even with the constraints of rules, though, CNN moderators could have charted a different course with the field they had been given. The meaningful divergence to explore on the stage would have been that between Sanders and Warren. Though they are allies on most issues and, apparently, intent on remaining such for now, the two are not without important differences in political economy and approaches toward confronting power.

Drawing out those contrasts might have required CNN to spend a few minutes reading up on Sanders and Warren, instead of treating the two as interchangeable stick-figure communists who will blow the presidential election. But doing so might have advanced understandings of the two figures on the stage with the most realistic chances of taking the nomination. Instead, those figures were pushed closer together by a shadowy composite opponent, who could call for working with the business community to stop medical bankruptcy without risking any standing in the polls.

In the next debates, in September, the qualifying thresholds will double to a modest 2 percent support in polls, which should eliminate roughly half the field from the stage. That might mean—might!—that the field will be small enough to place Elizabeth Warren, Bernie Sanders, Joe Biden, and Kamala Harris on the same stage along with reasonable long shots like Pete Buttigieg and Cory Booker. If Biden wants to make the case for caution, he’ll have to take that risk in person. The mini-Bidens, whose strength came from having almost nothing to lose, will have already lost it.