The ridiculous number of candidates on the Democratic stage Tuesday night created a fundamentally misleading aural and visual impression. Watching without access to polling data, you might have imagined that this was some sort of wild careening mess of a primary race, when really it’s remarkably consolidated.

There is a Joe Biden constituency that seems stable at around 30% of the primary electorate. There is an Elizabeth Warren constituency that has expanded swiftly enough, especially in early states, to make her arguably the front-runner. There is a Bernie Sanders constituency that is about two-thirds the size of Warren’s and Biden’s peak and seemingly stuck there. And then, way down at around 5% and under, there is everybody else.

So a big question in this debate and in the ones before Iowa arrives and the also-rans begin to be formally run out is whether Democratic voters can be persuaded to reconsider this consolidation. And last night there were only really two candidates who presented themselves as plausible vehicles for that reconsideration: Pete Buttigieg and Amy Klobuchar.

As for the others — well, Andrew Yang and Tulsi Gabbard are too niche, Beto O’Rourke is too limp, Julián Castro is too forgettable, and Tom Steyer is too absurd. Meanwhile, Kamala Harris and Cory Booker should be contenders, but Booker manages to be appealing at every debate without quite finding a rationale for his candidacy, while Harris has been on a weird self-destruct mission ever since her brief ascent — with her strange fight with Warren on Tuesday night over whether Twitter should ban Donald Trump a particularly peculiar self-charted nose-dive.

That leaves Buttigieg and Klobuchar, who both did well for themselves by arguing explicitly with Warren from more centrist ground and embracing the clearest rationales for their candidacies — which happen to be the same basic rationale: that they’re problem-solving Midwesterners with realistic policy blueprints who can win swing states, and (less explicitly) that they’re like Biden in their practicality and electability but unlike him in their relative youth and lack of baggage.

Buttigieg is smoother than Klobuchar and probably has more appeal to liberals and big donors, but Klobuchar has more political success under her belt and probably has more appeal to Obama-to-Trump voters. That makes the Minnesota senator the more compelling on-paper choice for Democrats who want electability and worry about Biden’s weaknesses: A Klobuchar-Booker ticket seems like where these Democrats should settle, if these things could be arranged through some purely pragmatic calculation.

They can’t be, though, and in particular there’s no party-decides arrangement that can induce the Biden coalition, durable across every debate so far, to fracture and then reform around someone who lacks his record, name recognition and credibility with party regulars. Nor is there a way to somehow combine strengths: Just as a Cruz-Rubio-Kasich chimera might have beaten Donald Trump in 2016, the strengths of Klobuchar and Buttigieg and Booker together could be formidable — but alone they each play to a much smaller base of support than do the consolidated front-runners.

And for Klobuchar and Buttigieg, race is a particular impediment: The moderate wing of the party is increasingly black and Hispanic rather than white and Midwestern, and neither candidate is well-positioned, in biography or record, to peel minority votes away from Biden. So both are stuck hoping to make Iowa their moment — a more reasonable hope for Buttigieg given his current polling numbers but not a completely vain one for Klobuchar.

The trouble is that their limitations mean that if either actually won Iowa, they could create the true free-for-all that the crowded debate stages promised — but they could also wound or cripple Biden without taking enough of his overall support to take his place, making the path to the nomination that much clearer for the candidates of the left.

Which, in turn, becomes another factor reinforcing the consolidation of the Democratic field. If you didn’t want Warren or Sanders a few months ago, it might have seemed too early to seriously consider anyone but Biden. But now, with Warren’s path seemingly opening, for the candidates presenting themselves as compelling Biden substitutes it might already be too late.