Matt Rourke / AP

Updated at 2:37 p.m. ET on March 2, 2020.

The sudden withdrawals of Pete Buttigieg and Amy Klobuchar from the Democratic presidential field sharpen one of the race’s most important remaining questions: How will college-educated white voters split if the contest narrows into a binary choice between Bernie Sanders and Joe Biden?

One of the most surprising trends of the primary’s early stages is that even as the Democratic Party grows more dependent on white-collar suburban white voters, the candidates those voters most favor have failed to gain traction. Buttigieg finished first among college-educated white voters in Iowa, second in New Hampshire and Nevada, and third in South Carolina. Elizabeth Warren and Klobuchar, who quit the race today with plans to endorse Biden, have also run well with this cohort.

With Biden reaffirming his advantage among African Americans in South Carolina on Saturday and Sanders running well among Latinos and working-class white voters, college-educated white voters may be the piece of the Democratic coalition that remains the most fragmented. The departures of Buttigieg and Klobuchar, the fading prospects of Warren, and the possibility that Michael Bloomberg’s campaign could look much less viable after Super Tuesday are combining to create a huge vacuum.

Whether Sanders or Biden can fill that space among college-educated white voters could prove a crucial factor in a potential one-on-one contest. “This is the demographic that likely determines if Biden or Bernie wins,” the Democratic pollster Andrew Baumann, who is not affiliated with any campaign, told me last night. “My money is on Biden.”

Buttigieg’s departure in particular is the rare event whose long-term implications may be easier to see than its near-term ones. By leaving when he did—amid some Democratic fears that the moderate vote is being split among too many candidates—Buttigieg added to the well of goodwill he established during his impressive ascent. After his remarkably sure-footed performance as a candidate, his future as a presidential contender—and likely a Cabinet officer if Democrats win in 2020—seems assured.

Yet his departure’s significance for this primary may be less predictable. The immediate reaction of many Democrats was that most of his voters would flow toward Biden. That wasn’t an unreasonable conclusion: Buttigieg has generally drawn more support from moderates than liberals, and his speech last night raised alarms about the direction Sanders would set for the party.

But others are cautious about assuming that most of Buttigieg’s remaining backers will switch to Biden, whose nostalgia for the clubby Washington, D.C., of old drew regular scorn from the former mayor of South Bend, Indiana. (That might change if Buttigieg endorses Biden, as he’s reportedly considering doing.) “As always, it’s complicated,” the longtime Democratic strategist James Carville told me after Buttigieg quit the race. “It’s not as clean as most [people] think. Warren is a factor here.”

Indeed, the biggest tactical question following Buttigieg’s departure is whether his supporters re-sort more along ideological or class lines. At his events in Iowa and New Hampshire, I found more voters considering Warren—another brainy, policy-focused candidate—than either Biden or Sanders. (The same was true of Buttigieg at Warren events.) The link seemed less about ideology than about demonstrable fluency and expertise. By contrast, white-collar voters drawn to Klobuchar, who centered her appeal on her grounded midwestern common sense, may find the transition to Biden an easier one. Another reason: In Iowa and New Hampshire, the states where Klobuchar ran best, her support tilted more heavily toward moderate voters than Buttigieg’s did.

So far, neither Sanders nor Biden has proved himself particularly well-suited—especially in stylistic terms—for the white-collar white voters common at events for Buttigieg, Warren, and Klobuchar. Sanders’s best showing among white voters with at least a college degree was in Nevada, with 24 percent, according to the entrance poll; in the other states that have voted, he hasn’t exceeded 21 percent of their vote. Biden posted a very strong 39 percent among college-educated white voters in South Carolina, but before that his numbers had reached only 15 percent in Nevada, 16 percent in Iowa, and a bruising 6 percent in New Hampshire, according to the Election Day polls.

Instead, college-educated white voters have gravitated toward three lagging candidates. In Iowa, they gave a combined 61 percent of their vote to Buttigieg, Warren, and Klobuchar. In New Hampshire, it was 64 percent. Even in Nevada they provided a 52 percent majority of their vote to the three. That number declined in South Carolina, as those contenders looked less viable over time. But even there they captured one-third of the vote among college-educated white voters.

Looking forward to Super Tuesday, the latest CNN survey shows the trio drawing 43 percent of college-educated white voters in California, which is as much as Sanders, Biden, and Bloomberg combined. NBC/Marist polls released yesterday show Buttigieg, Warren, and Klobuchar at 45 percent among them in Texas (nearly as much as Sanders, Biden, and Bloomberg) and 38 percent in North Carolina (where the other three did combine for a majority). Among white voters without a college degree, Buttigieg, Warren, and Klobuchar took only about one-fifth of the vote in both the Texas and North Carolina polls.

The trio have faced common problems in the race. All have struggled to establish a beachhead with minority voters. While Buttigieg ran about as well among white voters without a college degree as among those with one, both Klobuchar and Warren have struggled to reach beyond their “wine track” base. While Warren still has a formidable fundraising and organizational base, she hasn’t finished anywhere near first in any of the four contests so far.

The result: A huge bloc of college-educated white voters is now parked with two candidates who just left the race and a third who, at this point, has a vanishingly small chance of actually becoming the nominee.

These voters aren’t guaranteed to become the tipping point in a Sanders-Biden race. They aren’t distributed as evenly across the upcoming states as white voters without a college degree are, so they may not shape the result in as many places. And there’s no assurance that they will coalesce behind one candidate. But there’s no question that there is enough of them to make a difference if they do.

In 2016, white voters with a college degree cast more than one-third of the votes in the Democratic primary, according to a cumulative CNN analysis of all the exit polls conducted that year. It’s highly possible that number will increase this year, as more white-collar white suburbanites, whose recoil from Donald Trump helped Democrats take control of the House in 2018, participate in the nominating process. Compared with the 2016 primaries, the share of the vote cast by college-educated white voters has increased in each of the Democratic contests this year except New Hampshire.

Yet so far, this growing group has drifted away from the chief currents of the competition, settling into the backwaters. Buttigieg’s withdrawal especially may offer these voters their first real chance to steer back into the mainstream of the 2020 race—and more directly influence its outcome.

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