Nate Silver, the political analyst at FiveThirtyEight, has developed a model of the Democratic race that forecasts that, should Joe Biden win Iowa, he has an 80 percent chance of becoming the nominee. But he might not come out on top of the current nearly four-way tie that polls show in that state. (He is currently running third, behind Pete Buttigieg.) Under a scenario where Biden loses Iowa, Silver gives Biden only a 20 percent chance of a delegate majority, with Sanders’s odds of becoming the nominee going up to 40 percent.

That prospect sends shivers down the spine of establishment Democrats. “We all know the opposition research that Trump could throw against Bernie,” one Democratic pollster told me. “It runs from his rigid left-wing voting record to the fact that he was so delusional as to honeymoon in the Soviet Union in the year before the Berlin Wall fell and when it was obvious the system was evil.”

Establishment Democrats believe that they still have a good chance to stop Bernie even if he does win Iowa. They say the party might come together under an Anybody But Bernie candidate. They also point out that under Silver’s model scenario where Bernie wins Iowa, there would be a decent chance that no one would come to the convention with a majority of delegates. In that event, on the second ballot, a group of party elders, or superdelegates, would be allowed to vote, and Bernie would likely be their last choice.