This year’s election cycle marks a generational turning point. For the first time, millennials will match baby boomers as a share of the electorate.

There are messages for both parties in polling data about the generation born after 1980. For Republicans who think millennials will outgrow their liberal tilt in the last two presidential contests: Don’t count on it. For establishment Democrats who hope Hillary Clinton can inherit Barack Obama’s young followers: Don’t take it for granted.

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