The Washington PostDemocracy Dies in Darkness

New Iowa poll shows Bernie Sanders leading — with some red flags

Highlights from Bernie Sanders’s campaign, in pictures

WASHINGTON, DC- JUNE 14: Presidential candidate, Bernie Sanders arrives at the Capital Hilton to meet with Hillary Clinton on Tuesday June 14, 2016. (Matt McClain/ The Washington Post)

By the time all of the votes were tallied after the 2008 Democratic caucuses in Iowa, Barack Obama had scooped up more than a third of the support of women in the state — 35 percent — matching his support among men.

But women were 57 percent of the caucus-goers who turned out, according to exit polls, so the fact that he did so well with women was important. Hillary Clinton did far better with women than did John Edwards, getting 30 percent of their support to Edwards's 23, according to those surveys. But Obama's strength with that high-turnout group was important.

It's somewhat hard to believe that in six days, next Tuesday morning, we'll be sitting here analyzing what happened in Iowa this time around, poring over what information we have to figure out how the caucus shook out. For now, though, all we have are tea leaves generated by various polls. And according to the patterns in the Quinnipiac University poll of Iowans released Wednesday morning, the future is hard to predict.

We know that Bernie Sanders leads Clinton by four percentage points in this new poll — 49-45 — basically where he was when Quinnipiac surveyed earlier this month. Martin O'Malley gets 4 percent, which is actually important and which we'll come back to.

Let's focus for now on the demographic breakdowns of support, which are frankly pretty stunning. Sanders does much better among men and much better among younger voters. Clinton does better with the complementary groups.

We've added little lines showing where each candidate's overall support lies to illustrate how much these levels deviate by demographic. Men are 14 points more likely to back Sanders than voters overall! That's a huge split.

In the Washington Post-ABC News national Democratic poll released Wednesday, that split doesn't exist, at least not at that level. Which raises the question of why Iowa is so sharply divided. Is it a function of the months-long campaign? An exaggeration derived from the higher margins of error in the subgroup? It's hard to know.

When Quinnipiac surveyed earlier this month, they also found a huge split on favorability ratings by gender. When you look at net favorability — the number of people who view a candidate favorably minus the number that view him or her unfavorably — Clinton and Sanders are not far apart among women. Sanders has a net favorability of plus-81 with women; Clinton's is +69. Among men? Sanders is +88 and Clinton is +29 — a massive gap.

Remember what happened in 2008, though. In 2008, women turned out more heavily than men at the caucuses. If the split is similar this time around, and if the Democratic race continues to be close, that's not ideal for Sanders's campaign.

What's more, Sanders's support is far heavier among the third of poll respondents who've never been to a caucus before. Clinton leads among those who have attended at least one. And as we noted Tuesday, when commenting on how Donald Trump's support is also higher among first-time caucus-goers (though far less dramatically), voting tends to be habit-forming. People who haven't voted before are much less likely to vote than those who have.

Sanders appears to have an advantage Trump doesn't: A strong field campaign. Sanders's team appears by all measures to be better prepared to get people to caucus, even as weather forecasts suggest a worse day for it.

But still. In Iowa in 2008, men voted less. In most elections, young people vote less, too, since they often move around more (meaning their voter registrations are out of date) or work weird hours. And Sanders's support in this poll self-reports that they're going into this thing new. Lots of red flags.

Which brings us back to O'Malley. The way the caucus works for the Democrats in Iowa is that people come together and assign a certain number of delegates to a candidate. For places with multiple delegates that need to be assigned, a candidate must hit a certain level of support to be assigned one — at minimum, 15 percent. If that mark isn't hit, people who are caucusing for that candidate have to move to someone else.

So let's say that Sanders's turnout isn't as strong as Clinton's on Monday, thanks to the factors above. That would make the race closer than it seems based on the poll. In nearly every caucus location — or perhaps, every location according to Cook Political — O'Malley backers have to move to Sanders or Clinton. Where they go isn't clear; recent polling doesn't give a good picture.

Meaning that lots of things could happen Monday night across the state of Iowa to shift votes one way or the other and dramatically change the outcome of the race. It's too close to call and too messy to call and too weird to call.

But we should have a very interesting morning Tuesday.