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Election Update: A New Batch Of Iowa Polls Still Shows A Tight Race Between Sanders And Biden

The Iowa caucuses are now just five days away, so pollsters are busy trying to give us their final looks at where the candidates are heading into Iowa. But for those of you hoping for a clearer picture of where things stand, I’m afraid there’s no such luck.

[Our Latest Forecast: Who will win the Iowa caucuses?]

Three new Iowa polls dropped today pointing to a still very close race between Sen. Bernie Sanders and former Vice President Joe Biden (though former South Bend, Indiana, Mayor Pete Buttigieg and Sen. Elizabeth Warren shouldn’t be written off). And topline numbers in our primary forecast show that Biden is still in the lead with roughly a 1 in 2 (45 percent) shot at winning a majority of pledged delegates, while Sanders has about a 3 in 10 (29 percent) chance of doing so.1 Buttigieg and Warren each have about a 1 in 20 (5 percent) shot.

Compared to yesterday’s election update, these figures represent a 4-point improvement for Biden and a 2-point decrease for Sanders. A fair bit of this has to do with fixing a bug in the model’s code — the model was giving candidates extra credit for wins in their home states and regions when it was supposed to be deducting credit instead (editor-in-chief Nate Silver has an explanation here). But it’s also because Biden led in two of the three new Iowa surveys whereas Sanders led in both Iowa polls we talked about yesterday.

In our Iowa forecast, Sanders still leads slightly (37 percent versus Biden’s 35 percent). This is unchanged from yesterday and is probably better thought of as a tie. Buttigieg and Warren’s chances haven’t really shifted in the last 24 hours. Although Sen. Amy Klobuchar did tick up a little today thanks to some double-digit showings in today’s batch of polls, though she remains a decided underdog with only a 3 percent shot at winning Iowa. On balance, though, the newest Iowa surveys held some good news for Biden compared to some other recent surveys where Sanders did better, though the Vermont senator did still manage to make gains in two of today’s polls:

  • First, Monmouth University found Biden in the lead with 23 percent, followed by Sanders at 21 percent, Buttigieg at 16 percent, Warren at 15 percent and Klobuchar at 10 percent. And even though Biden was the poll’s leader, he was actually down a point from where he was in Monmouth’s last Iowa poll from early January. Buttigieg also fell a point, while Warren’s numbers were unchanged. Sanders, on the other hand, ticked up three points from 18 percent to 21 percent, and Klobuchar two points (though both gains were within the poll’s margin of error).
  • Next, Morningside College made their 2020 debut this week with an Iowa poll that found Biden very slightly ahead of the field with 19 percent. (Buttigieg came in second at 18 percent.) Meanwhile, Sanders and Warren were tied with 15 percent support while Klobuchar had 12 percent.
  • Finally, contrary to what Monmouth and Morningside found, Iowa State University/Civiqs’s new poll found Sanders leading the field by 5 percentage points with 24 percent support. Warren came next at 19 percent, followed by Buttigieg at 17 percent, Biden at 15 percent and Klobuchar at 11 percent. But keep in mind that Iowa State/Civiqs has found strong numbers for Buttigieg and Warren in the past, so once we account for house effects, the model treats their results as 15 and 14 percent, respectively. At the same time, this pollster has generally had Biden polling worse than other pollsters, so his number bumps up to 18 percent. There’s less of a known house effect for Sanders, though, so our model keeps his support at 24 percent, up 3 points from the pollster’s December survey. (Buttigieg fell 7 points from December and Klobuchar gained 7 points. Biden and Warren’s numbers were roughly the same.)

Of course, we’re not just interested in the topline results in these polls either. We’re also keeping an eye on questions regarding Iowa voters’ second-choice preferences, as voters No. 2 could be important on caucus night because voters have to shift support to a new candidate if their initial choice doesn’t meet a certain level of support at their caucus site (usually 15 percent).

[Our Latest Forecast: Who Will Win The 2020 Democratic Primary?]

So if there’s one reason not to write Warren off, it’s that she was the top second-choice pick in both the Monmouth (19 percent) and Iowa State/Civiqs (16 percent) polls. In other words, if she can remain viable at most caucus sites, she could still benefit when some voters have to realign. At the same time, though, Monmouth found that if the field was limited only to the top-four candidates, Biden would lead with 29 percent, followed by Sanders at 25 percent, Buttigieg at 20 percent, Warren at 19 percent, so it’s unclear just how much room Warren has to gain as a popular second-choice pick.

One other thing to keep in mind that is going on under the hood with these polls is that pollsters are trying to gauge who is actually going to show up and caucus, a process that’s much, much more involved than simply casting a ballot like in a primary. University of Delaware political scientist David Redlawsk recently pointed out that some Iowa polls have small but meaningful differences in the age makeup of their likely caucus-goers, which may play some role in who’s doing better in a given poll. For example, the Iowa State/Civiqs poll found Sanders leading among 18-to-34 year olds with 33 percent while Biden got just 1 percent! But that survey estimated that 47 percent of likely caucus-goers will be under 50 years old, a boon for Sanders’s topline number, whereas the 2016 entrance poll found that just 42 percent of caucus-goers were under the age of 50. Of course, it’s difficult to say who is right when it comes to trying to figure out who is going to show up on Monday — will more young people caucus in 2020 than in 2016? The answer is we won’t really know until caucus night, but it’s just another thing to consider when looking at the topline numbers in these polls.

And while Wednesday was an Iowa-heavy polling day, there was one new national poll from The Economist/YouGov that found the race between Biden and Sanders tightening. In their survey, Biden led Sanders by just 2 points, 26 percent to 24 percent, with Warren in third at 20 percent. This was a strong poll for Sanders, who was at 18 percent in last week’s Economist/YouGov national survey and 28 percent for Biden. There isn’t a sizable house effect for either Biden or Sanders, though Warren tends to do well in Economist/YouGov surveys.

Bottom line: The clock is ticking for Democrats in Iowa. Candidates don’t have much time left to make last-minute appeals and undecided voters can’t vacillate between candidates for much longer either. As recent polls and our forecast show, it’s shaping up to be a very competitive and potentially unpredictable contest — quite possibly the most competitive Iowa caucuses ever.


  1. As of 7:50 p.m. Wednesday evening.

Geoffrey Skelley is a senior elections analyst at FiveThirtyEight.