“FOR every blue-collar Democrat we lose in western Pennsylvania,” Chuck Schumer famously said in 2016, “we will pick up two moderate Republicans in the suburbs in Philadelphia. And you can repeat that in Ohio and Illinois and Wisconsin.” Hillary Clinton went on to lose three of those four states, costing her the presidency. But just as the Democrats seemed poised to turn their backs on college-educated white voters, this historically Republican group has emerged as a probable decisive factor in propelling the Democrats to regain control of the House of Representatives in November.

In the wake of Mrs Clinton’s defeat, progressives seized on her loss to argue that “country-club Republicans” would never defect to a party that sought to raise their taxes. Recently published data refute this claim: Mrs Clinton now appears to have fared far better with well-educated whites than was previously believed. According to the national exit poll published on the night of the presidential election, Donald Trump won white college graduates by a margin of 48% to 45%. But in July, the New York Times published an analysis of voting records by precinct—a far more granular source of information than the county-level data available in 2016—that showed Mrs Clinton narrowly winning white neighbourhoods where around two-thirds of voters had college degrees (and those with even higher educational attainment by ever-greater margins). In contrast, in his successful re-election campaign in 2012, the only heavily-white precincts where Barack Obama prevailed on average were those where over 90% of voters were college-educated.

Then on August 9th, Pew Research Centre, a polling firm, released a study of the electorate of 2016 using a file of responses from 3,000 people it could independently confirm had actually voted in that election. It found that Mrs Clinton had won white voters with college degrees by a comfortable margin of 55% to 38%.

If Mrs Clinton’s strategy of winning over well-educated whites was a success, why did she lose? The simplest answer is that her approach was a poor fit for the electoral college that America uses to select its president. Although she won the popular vote by 2.1 percentage points, the states with the narrowest vote margins happened to have disproportionately high shares of whites without college degrees, such as New Hampshire and Wisconsin. In contrast, the states where educated white voters were most abundant were uncompetitive: either ones Mrs Clinton would have won anyway, like California, or those where she was too far behind, such as Texas.

By contrast, in 2018, the voting bloc Mrs Clinton successfully wooed is likely to be unusually influential. Because Democrats already have the vast majority of urban districts and Republicans a similar share of rural ones, those that will decide control of the House of Representatives are primarily suburban. And the suburbs happen to be precisely where white college graduates tend to congregate: in the 38 districts currently rated by the Cook Political Report as either “toss-ups” or merely “leaning” towards one party or the other, an average of 28% of over-25s are white and have a college degree, compared with 22% in all other races.

Sceptics—and Republican partisans—might retort that these voters’ distaste for Mr Trump did not extend to his party’s congressional candidates in 2016. In 23 different districts, voters supported Mrs Clinton for president while electing a Republican to the House; 27% of the population aged over 25 in these split-ticket seats are white college graduates. However, at the time of the 2016 election, Congressional Republicans still enjoyed a separate brand from Mr Trump’s: many of them publicly disowned him in response to the release of a recording in which he bragged about groping women.

Nearly two years later, however, members of the president’s party are politically yoked to him, no matter how much they may seek to distance themselves. And so far this year, when voters have had the opportunity to choose between Democratic and Republican congressional candidates, they have tended to ditch the latter. On August 7th, the state of Washington held a “top-two” primary, in which all candidates appear on a single ballot and the two leaders advance to the general election. Running against Jaime Herrera Butler, a four-term Republican incumbent, the Democrats’ collective vote share was six percentage points higher than it was during the primary in 2016; those seeking to unseat Cathy McMorris Rodgers, the highest-ranking Republican woman in the House, improved on the party’s performance in 2016 by 11 points. Two months earlier, Democrats running in California’s top-two primary racked up gains that were nearly as impressive. And in both states, educated white voters appeared to be unusually likely to abandon the Republican ship: districts with high shares of them swung towards the Democrats by unusually large amounts (see chart).

But just as Republicans may be paying the price for alienating college-educated whites, Democrats should be wary of relying on them too heavily. In special elections, the party has failed to flip districts where they are plentiful, such as Georgia’s 6th and Ohio’s 12th (though it did register impressive gains in both races). Any path to a majority will probably involve a combination of retaining Mrs Clinton’s gains with this group and bringing some of the working-class whites who backed Mr Obama and then Mr Trump back into the fold. But if the country-club set does spearhead a successful Democratic campaign in November, Mr Schumer will at last be able to claim that his electoral analysis from 2016 was simply early, rather than wrong.