With Sen. Bernie Sanders (I-Vt.) surging in both state and national polls heading into Monday's Iowa caucuses, he seems likely to be the first choice of a plurality of caucus goers in the state. But due to the unique structure of voting in Iowa, he might win, but also not win. And that means that instead of a clear victor heading into New Hampshire next week, Democrats might be dealing with another insufferable squabble over rules and narrative.

In past caucus years, party officials reported only the state delegate totals, essentially black-boxing the two other results inside the caucus sites. This year will be totally different. The state party will be releasing the "first alignment" — the initial preference tallies for each candidate at all the precincts. Supporters of candidates who failed to meet a 15 percent threshold at the individual caucus are then released. They can just go home and watch Netflix. Or they can try to build a coalition for one of the non-viable contenders, or join the supporters of someone with more than 15 percent. When that process is complete, a tally is taken of this new "final alignment." And then those totals are translated into something called "state level delegate equivalents," which are used to estimate the final distribution of Iowa's 44 delegates.

Polling of the Iowa caucuses is notoriously difficult and volatile, and we will not have a final survey from the state's best pollster, the Des Moines Register. Just going by the averages and the momentum, Sanders would seem to have the edge. As of Sunday afternoon, he was at 24.2 percent to former Vice President Joe Biden's 20.2 percent. But this year there are an unusual number of candidates who might tally in the double digits but fail to meet the viability threshold at dozens or even hundreds of caucus sites. And they could wreak absolute havoc on the post-Iowa narrative.

Sen. Elizabeth Warren (D-Mass) and former South Bend Mayor Pete Buttigieg are both polling just above 15 percent in the Real Clear Politics average. But Buttigieg has bled out 8 points since December, and seems certain to miss the cut in some places, particularly in Sanders-leaning urban areas. Warren, who led the state polling in October, has also dropped to the point where some surveys have her at less than 15 percent. And Sen. Amy Klobuchar (Minn.) is moving in the other direction — she has hit 10 percent or more, but not 15, in four different Iowa polls this month after struggling throughout the campaign to get out of the low single digits. Even Andrew Yang and Tom Steyer are both over 3 percent.

Add it all up, and close to 50 percent of votes from that first alignment might be on the move at many sites. How exactly that plays out really depends on which pollster has this electorate right. If Sunday's CBS/YouGov poll is closest, Sanders, Biden, Warren, and Buttigieg will all clear 15 percent statewide, and at most caucus sites. That will leave very little to redistribute from lesser candidates and means that the final delegate totals should correspond pretty closely to those first alignments. Sanders would win, but the final delegate tallies would be narrowly divided between the big four. But if Sunday's Emerson poll is more on target, only Sanders (28 percent) and Biden (21 percent) are sure to clear 15 percent, leaving 50 percent of the vote from Warren, Klobuchar, Buttigieg (who is right at 15), and the lesser candidates to realign (again, the precise dynamics depend on totals at the individual caucus sites).

That means that, like in a Ranked Choice Voting system, second preferences could be decisive. And that's where Sanders is really in trouble. A recent Iowa State/Civiqs poll broke down second preferences by candidate. Just 6 percent of Buttigieg boosters would go to Sanders. He also gets only 9 percent out of the large group of "others" that includes Klobuchar, Yang, Steyer, and Rep. Tulsi Gabbard (D-Hawaii). Unsurprisingly, a third of Warren's voters would go directly to Sanders (and vice versa).

Klobuchar could therefore be the pivotal figure in this race. Last week's Monmouth poll (which showed Biden leading Sanders narrowly), had 40 percent of Klobuchar voters moving to Biden, 25 percent to Buttigieg, and 20 percent to Warren. You can dig through the cross-tabs on a dozen polls and find pretty similar findings: Sanders isn't a leading second-choice candidate generally, and only pulls disproportionately from his closest ideological rival, Warren. In that sense, the best thing for Sanders is probably for Warren to underperform her final polls, and fail to hit 15 percent at many caucus sites, and for Klobuchar and Buttigieg to both hit viability thresholds in as many places as possible.

The campaigns are obviously aware that the final delegate totals might look nothing at all like the polling averages, and that the shift after the first alignment might not be super friendly to Sanders. And it seems like the Sanders campaign knows this too, and is preparing to argue that he is the real winner of the caucuses if he triumphs in first alignment totals but not the final delegate count. The New York Times asked all the campaigns which of the three totals they would choose to highlight after the results are known. The Sanders campaign declined to comment (as did Warren) but the Times noted that earlier this month, top aide Jeff Weaver said, "At the end of the day, I think that the first impression is probably the most accurate portrayal of who won the night."

The best thing for the party would be for the candidate who wins on the first alignment to also win the most delegates. And the worst thing, probably, would be for this race to start with both the Sanders and Biden campaigns claiming victory in Iowa — or worse still, both Sanders and Warren. That's true whether you think the first alignment or the final delegate totals should determine the real winner. Nerves are still raw from 2016's divisive grudge match, and Sanders supporters in particular are primed to seize on procedure as evidence that the party is rigging the race against their candidate.

Of course, none of this might matter in the end. If there is late movement toward Sanders, he could win all three tallies decisively and run away with it. Or Biden might win all three counts. Warren and Buttigieg are both still close enough to conceivably win. And there are still enough undecided voters and uncertainty to put even Klobuchar over the top. But if there is a dispute over the results, Iowa Democrats should really ask themselves whether in this case, they might have erred on the side of providing too much transparency. And national Democrats should take a long (and long overdue) look at why they let overwhelmingly white Iowa's baffling hodgepodge of weird rules and practices have this much influence in their nominating contest.

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