Harry Enten puts his finger on something today that has intrigued Iowa-watchers (and hey! who isn’t?) the last few years: the state’s love affair with Barack Obama definitely seems to have cooled.

There are a lot of factors that went into Joni Ernst’s victory last week, most notably the terrible gaffe committed by Bruce Braley in front of an audience of out-of-state trial lawyers concerning Chuck Grassley the “Iowa farmer,” which violated multiple Iowa taboos. But as Enten notes, Obama’s approval rating had been significantly sagging in Iowa–and running below his national average–since the state gave him a 2012 win by a bit under six percent of the vote.

Arguably Obama’s high popularity in Iowa in his two election years led us all to forget this was the most marginal of purple states before then, being carried by Al Gore by just over 4,000 votes in 2000 and by George W. Bush by 10,000 votes in 2004. The 2008 Iowa Caucuses launched Obama’s presidential campaign, and he never forgot that, constantly returning to the state to thank its voters for the special role they played in his career. That mutual regard is obviously fading. But Enten has a theory that it reflects something of particular danger to Democrats:

Here’s one explanation: White voters in Iowa without a college degree have shifted away from the Democratic Party. And if that shift persists, it could have a big effect on the presidential race in 2016, altering the White House math by eliminating the Democratic edge in the electoral college.

There are a lot of white voters in Iowa without a college degree, and they have differed politically from their demographic counterparts nationally. In 2008, President Obama won non-college whites in Iowa by 6 percentage points; he lost them nationally by 18 points. In 2012, college-educated and non-college-educated whites both broke by about 6 percentage points for Obama. That’s very different from nationwide, where Mitt Romney won non-college whites by 25 percentage points while winning college-educated whites by 14 points.

In the run-up to this year’s midterm elections, polls showed Iowa’s white voters behaving normally — well, normally abnormal — favoring the Democrat more than their demographic kin nationally. Last month, two Marist polls showed Braley trailing by 5 percentage points among Iowans with a college degree and down an average of just 1.5 points among those without a college education.1 Overall, Braley was down by only 2.5 percentage points, on average, in Marist’s October surveys.

According to the exit polls, however, Braley lost non-college-educated voters of all races by 10 percentage points. His performance among the college-educated matched pre-election polls. But among non-college whites, Braley lost by 14 points.

Now that could mean Braley-the-Trial-Lawyer-and-Disser-of-Iowa-Farmers was particularly distasteful to the white working class, or that an unusual affection for Obama among Iowans in the past had propped up Democratic margins. The latter possibility could definitely matter in 2016, and if it also reflects a general downward trend of Democratic support among non-southern non-college-educated whites, that’s a bigger problem.

Ed Kilgore

Ed Kilgore is a political columnist for New York and managing editor at the Democratic Strategist website. He was a contributing writer at the Washington Monthly from January 2012 until November 2015, and was the principal contributor to the Political Animal blog.