Read: The midterms could be a landmark election for women.

“There are two electorates: One is comfortable with the changes and diversity, and they are part of that change and diversity; and there is an electorate that is shrinking and is uncomfortable with that change because they see that change as a threat,” says Cornell Belcher, a Democratic pollster who closely studies black voting patterns. “And they are doing battle for the future of this country.”

Evidence from the Trump era suggests that these inverse dynamics—the increasing diversity of the Democratic-candidate roster and the growing appeal of racial nationalism inside the GOP coalition—may feed on each other.

From one side, Trump’s overt appeals to white racial anxieties about immigrants, Muslims, and black football players, as well as his derogatory comments about women, inspired unprecedented numbers of minority and white female candidates to seek office as Democrats. “We all know that there is the Trump effect going on among women and people of color, and the sense that there is something very significant at stake, perhaps in a clearer way than ever before, that needs to be fought for,” Carter says.

But from the other direction, the diverse slate of Democratic candidates provides a powerful symbol of social change that may make more white voters receptive to the message of racial solidarity from Trump and other Republicans. In this way, the same underlying force—a political debate that’s more and more centered on questions of national identity and cultural affinity, rather than on economic interests—is pushing Democrats toward embracing a changing America and pushing Republicans toward resisting it.

Whatever the results next month, this election will likely be remembered as a crossing-the-Rubicon moment when the diversity of the Democratic candidates for the first time approximated the diversity of the party’s electoral coalition. (A comprehensive post-2016-election study by the Pew Research Center concluded that minorities accounted for 40 percent of Hillary Clinton’s votes that year, compared with just 12 percent of Trump’s.)

According to the Reflective Democracy Campaign’s calculations, white men make up only 42 percent of the Democratic candidates for the House, the first time they have fallen below half. As recently as 2014, white men still represented 55 percent of Democratic House candidates. Now, though, white women (at 30 percent), nonwhite men (at 17 percent), and nonwhite women (at 11 percent) combine for the majority.

White men have also fallen below the majority among Democratic candidates for the Senate (46 percent) and state legislatures (just 41 percent). In both of those categories, white women rank next, followed by men of color and nonwhite women.

This shift is evident in a wide array of high-profile races. Democrats have nominated Latino candidates for governor in Texas, Arizona, and New Mexico (though only Michelle Lujan Grisham in the last state is given a strong chance). And they’ve nominated black candidates for governor in Florida (where Andrew Gillum leads in most polls), Georgia (where Stacey Abrams is locked in a razor-tight race), and Maryland (where Ben Jealous trails the popular Republican incumbent, Larry Hogan.)