A Failure of Mobilization
Before the 2016 election, Democrats like Senator Chuck Schumer (NY) bragged that, “For every blue-collar Democrat we lose in western Pennsylvania, we will pick up two moderate Republicans in the suburbs in Philadelphia, and you can repeat that in Ohio and Illinois and Wisconsin.”
As the chart below shows, the preferred candidate of the poor was no-one, with nearly 1-in-2 not voting. Schumer was correct that Democrats performed well with the wealthy, but those voters make up a tiny, albeit influential, sliver of the electorate. These low-income nonvoters would overwhelmingly prefer Democrats if they voted, and would have been more than enough to shift the election outcome in favor of Democrats.
Poor voter turnout from low-income voters was at least partially for lack of trying, as data from the Cooperative Congressional Election Studies 2016 show.
The chart below shows reported contact rates by income. Even when examining only individuals who were matched to a voter file, or matched to a voter file and registered Democratic in a swing state (people we would expect Democrats to contact), there are deep class divides in reported contact. Among registered Democrats living in a swing state* earning less than $50,000, 65 percent reported contact, compared to an 80 percent contact rate among Democrats living in a swing state earning more than $100,000.
Democrats also struggled to mobilize people of color, with Black turnout dropping off dramatically from 2012, and persistent racial gaps in turnout remaining. One possible cause is lack of aggressive mobilization.
As the chart below shows, even when examining only individuals who are registered as Democrats, there were racial disparities in contact. There is also strong evidence that descriptive representation (young people, people of color, and women holding political office) increases turnout.