But Democrats will be operating with very little margin for error if they must win back the House almost solely by capturing white-collar suburban seats. Their path would be much easier if they could also win a respectable number of the Republican seats they are targeting outside of the major metro areas, including districts in upstate New York, northeastern and southwestern Iowa, downstate Illinois, California’s Central Valley, and Washington State, where Republican Representatives Cathy McMorris Rodgers and Jaime Herrera Beutler both showed weakness in Tuesday night’s primary.

Ohio’s special election is a blue-wave red alert

Democrats, and outside election handicappers, like their odds in several of those races (especially given the agricultural community’s unease over Trump’s ongoing trade wars). But Balderson’s big margins in such blue-collar and small-town counties as Marion, Morrow, and Muskingum are reminders of how strong a headwind Democrats must overcome in those places.

It was a measure of the difficult environment confronting Republicans that Democrats effectively competed for this district at all. Since the seat was reconfigured in 2010 to make it more safely Republican, former Representative Pat Tiberi never carried less than 64 percent of the vote. Trump carried the district by 11 percentage points four years after Mitt Romney won it by 10. Moreover, the seat is preponderantly white (86 percent) and contains substantial numbers of the small-town and rural voters who have flocked to Trump. But it also houses a large contingent of college-educated white voters (about 40 percent), who have conspicuously provided Trump much less support than a Republican president typically enjoys.

Strategists in both parties agree that the recoil from the president among those voters, particularly women, was the principal reason the race became competitive. And despite Balderson’s lead, the results from the Ohio district’s suburban areas is sure to compound the anxiety of House Republicans defending seats in white-collar communities in and around Philadelphia, Minneapolis, Chicago, Denver, Detroit, Charlotte, Miami, Los Angeles, Seattle, and New York—and perhaps even Dallas, Houston, and Kansas City. Many of those seats are both less monolithically white and less rural than Ohio-12, which increases the Republican risk.

Balderson was roundly rejected Tuesday in the parts of the district located in the affluent, well-educated, and diverse Franklin County. In 2012, Barack Obama carried those areas by three percentage points; in 2016, Hillary Clinton expanded that margin to 18 points over Trump, according to calculations by Ryan Matsumoto, an analyst for the independent publication Inside Elections. On Tuesday, O’Connor beat Balderson in those Franklin County areas by fully 30 points. Moreover, the county turned out at a relatively high level.