But there’s no guarantee Democrats can reap big benefits from Millennial mistrust of Trump. The best evidence is that turnout among Millennials remained mediocre in 2016—and, based on historic patterns, could decline more substantially in the 2018 midterm election than among older voters. And while Trump faces grim numbers among Millennials overall, he has displayed strength among them with the same groups that responded to him most in older generations: evangelical, non-urban, and blue-collar whites.

Kristen Soltis Anderson, a GOP pollster who has written a book about Millennial voters called The Selfie Vote, agrees that Trump could stamp the GOP with an identity that causes lasting problems with the generation. But she also sees opportunities for inroads. “There are a lot of things about the Millennial generation that I still believe are completely at odds with Trumpism,” she said. “But that’s not to say that if Trump is succeeding as president some of those minds couldn’t be changed.”

The stakes in the parties’ struggle for Millennials’ allegiance are steadily rising as their numbers in the electorate increase. In 2000, the first presidential election when Millennials were eligible to participate, baby boomers outnumbered them by almost exactly 10 to 1 as a share of eligible voters. In 2016, according to calculations by the non-partisan States of Change project, Millennials for the first time equaled baby boomers as a share of eligible voters, both representing just over 30 percent. In 2020, the project expects baby boomers to decline to about 28 percent of eligible voters, while Millennials expand past 34 percent and the first post-Millennials—born starting in 2001—establish a beachhead as roughly another 3 percent of the eligible electorate. (If those projections hold, it will mark the first time since 1978 that baby boomers aren’t the largest generation of eligible voters.) By 2024, the project forecasts, Millennials and post-Millennials will represent nearly 45 percent of all eligible voters, while baby boomers will sink back to about one-fourth.