What an Iowa Poll From The Des Moines Register Could Tell Us About the 2024 Race

What That Surprising Iowa Poll Might Be Telling Us

Sometimes outliers are early indicators, capturing something other polls just haven’t measured yet. Other times, they’re a fluke.

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By Kaleigh Rogers

Kaleigh Rogers has been covering election polling since 2019.

Over the weekend, people who pay close attention to political polls received a November surprise: a well-respected poll showing Vice President Kamala Harris leading in Iowa by three percentage points.

Iowa has not been considered a swing state in the presidential race. Former President Donald J. Trump won the state by eight points in 2020, and every other poll there this year has shown him with a lead of at least four points. The Cook Political Report rates Iowa as “solid Republican.”

The new poll was startling, and actually caused some jostling in online prediction markets, in part because of the source: the revered independent pollster J. Ann Selzer, who is one of the most highly rated practitioners in the country and has a track record of exemplary work.

But as I’ve written before, polls are best understood in aggregate, and any single poll by itself is prone to a certain amount of error. Overall, Mr. Trump still has a three-point advantage in The New York Times’s polling average of Iowa, even with the new Selzer poll included.

So why the uproar over this single poll, and what should voters make of it as we head into Election Day?

The poll has caused so many pundits and politicos to sit up because Ms. Selzer has been here before. In the final week before the 2020 election, Ms. Selzer released a poll of Iowa conducted with The Des Moines Register that showed Mr. Trump leading by seven points in the state. It was an outlier; other polls showed a much tighter race, with averages showing Mr. Trump ahead by just over one point. Ms. Selzer’s own poll from September of that year had shown Mr. Trump in a tie with Joe Biden.

Mr. Trump won Iowa that year, by 53 percent to 45 percent, an eight-point margin of victory.

“I’ve been the outlier queen so many times,” Ms. Selzer said in a phone interview on Monday. “I’m not jumpy.”

Ms. Selzer produced a similar outlier poll in 2016, when she showed Mr. Trump up by seven points, despite polls overall giving him a slimmer, three-point lead. He won the state that year by nine points.

Perhaps some readers even remember the time Ms. Selzer released a poll showing that a relatively unknown senator from Illinois was in the lead heading into the Iowa Democratic caucuses in 2008, a shock to pretty much everyone. You probably know how that story ends: with Barack Obama winning the Iowa caucuses, opening up his path to the presidential nomination and the White House.

But even Ms. Selzer was surprised by this latest poll finding. “‘Surprised’ doesn’t quite do it justice,” she said. “It had not crossed my mind that we would show a Harris lead.” After examining the data and discussing it with journalists at The Register, which sponsored the poll, she said that they hadn’t seen any obvious flaws. In fact, she had found some underlying results that explained what may be happening.

A poll Ms. Selzer conducted for The Register in September, which showed Mr. Trump with a four-point lead over Ms. Harris, was already revealing a shift toward the vice president, Ms. Selzer said. In that poll, and in the latest one, she said, the share of voters who said they were “very likely” to vote (or, in the latest poll, had already done so) was higher than in a poll they had fielded in June.

More female, younger and college-educated voters were now saying they would vote — groups that tend to support Ms. Harris.

In the latest poll, voters 65 and over also favored Ms. Harris, particularly women in that age bracket, who backed the vice president two to one, 63 percent to 28 percent. And independent voters, particularly independent women, also shifted toward Ms. Harris in the new poll.

“It is as though people got off the bench and said, ‘All right, I’m voting.’ And that was Harris supporters,” Ms. Selzer said.

Even if Ms. Harris doesn’t win in Iowa, which has only six electoral votes, the idea that she may be making gains in a Midwestern state could give Democrats hope for her chances in battleground states like Wisconsin and Michigan.

But the fact remains that the new poll is an outlier, since all other polling up to this point has suggested that Mr. Trump will win Iowa comfortably. And Ms. Harris’s lead in the new Selzer poll is within the margin of error of plus or minus 3.4 percentage points. That means a closer result, or a Trump win by as many as three or four points, are all possibilities within that range.

Ms. Selzer said she is “prepared” for Mr. Trump to win in the state, and isn’t worried that her poll might turn out to be wrong. “At the end of the day, I’ll either be golden — I hope for that — or I’ll be a skunk,” she said. “So, what am I going to do if I’m a skunk? I’m going to take it like a big girl. No tears will be shed.”

Pollsters can sometimes succumb to a phenomenon known as herding, when they release their results only if they align with what has already been established by earlier polls. Ms. Selzer’s willingness to share her results even when they are anomalous is part of why she is widely regarded as a trustworthy pollster.

Outlier polls are part of the story of every election cycle. Sometimes they are early indicators, capturing something other polls just haven’t measured yet. Other times they’re a fluke, a product of the normal error that can seep into any poll. In this case, we’ve run out of time to test whether other polls find a similar shift to Harris in Iowa. What is left is the only poll that actually matters in the end: the election itself.