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.