Iowa Democratic Presidential Caucus

[BlueMTexpat]

2. What should perhaps concern you

more per this OP is that 43% of voters included among the top three candidates do not list Biden as their first preference.

If one includes the top four, that percentage mounts to 57% who list others as their first preference.

Several pollsters have stated that EW is most often stated as the second choice among Sanders, Harris and Buttigieg voters. See, e.g., https://theweek.com/articles/869637/how-elizabeth-warren-could-sweep-2020-primaries

... Despite her recent surge, Warren still trails Biden slightly in national polling averages. While she leads in Iowa, she's still slightly behind Biden in New Hampshire and both Biden and Sanders in Nevada. There's plenty of time for Biden, Sanders, or even one of the lower-polling candidates to make a run between now and when voting starts. But there are reasons to think that she will continue to rise. She's making inroads with black voters who will be so critical in South Carolina and in many Super Tuesday tilts. She has the highest enthusiasm numbers of any of the Democratic candidates and is the predominant second choice of Sanders, Harris, and Pete Buttigieg voters. [emphasis mine] When YouGov asked respondents if they would be "disappointed" if certain candidates got the nomination, only 7 percent said so about Warren. Sixteen percent expressed disappointment with a Sanders nomination and 22 percent with Biden.
...

In 2016, the actual Iowa caucus result was almost evenly split (49%+) between Hillary and Bernie, with Hillary having a tiny edge.

While 2020 polling numbers will continue to change many times between now and the real numbers, these early primary polls are nowhere near where we ended up in 2016. Most significantly, Biden's numbers do not seem to be increasing.