Millennials Are Not an Exception. They’ve Moved to the Right.

Fifteen years ago, a new generation of young voters propelled Barack Obama to a decisive victory that augured a new era of Democratic dominance.

Fifteen years later, those once young voters aren’t so young — and aren’t quite so Democratic.

In the 2020 presidential election, voters who were 18 to 29 in 2008 backed Joe Biden by 55 percent to 43 percent, according to our estimates, a margin roughly half that of Mr. Obama’s 12 years earlier.

The exit polls show it even closer, with Mr. Biden winning by just 51-45 among voters who were 18 to 27 in 2008 (exit polls report results among those 30 to 39, not 30 to 41 — the group that was 18 to 29 in 2008).

And last fall, the young voters of ’08 — by then 32 to 43 — preferred Democratic congressional candidates by just 10 points in Times/Siena polling.

This shift toward the right among the young voters who propelled Mr. Obama to victory 15 years ago is part of a larger pattern: Over the last decade, almost every cohort of voters under 50 has shifted toward the right, based on an analysis of thousands of survey interviews archived at the Roper Center.

It’s not necessarily a stunning finding. Political folklore has long held that voters become more conservative as they get older. But it is nonetheless at odds with a wave of recent reports or studies suggesting otherwise. The Financial Times, for instance, wrote that “millennials are shattering the oldest rule in politics” by not moving to the right as they age. Similarly, the Democratic data firm Catalist found that Democrats essentially haven’t lost ground among millennials and Gen Z over the last decade. These findings have helped spark a new wave of speculation about whether the long-awaited era of Democratic dominance might this time really be at hand.

But a different story emerges by tracking the same cohort of voters over time, rather than a whole generation with changing composition. The millennials of 2008 are not the same as those of 2016, for instance: Six additional years of even more heavily Democratic millennials became eligible to vote after the 2008 election, canceling out the slight Republican shift among older millennials.

The shift to the right appears largest among the oldest “young” voters — the older millennials who came of age in a very different political era from today. Many of the issues that drew young voters to the Democrats in 2004 or 2008 — like the Iraq War or same-sex marriage — may no longer be issues at all. Republicans may have even reversed their former disadvantage on some issues, whether by sometimes opposing foreign intervention, winning some voters with colorblind messaging on race, or by becoming the “anti-establishment” party.

In contrast, the shift to the right is more modest among younger voters — especially those who came of age after Mr. Obama, in the era of Black Lives Matter, the Bernie Sanders campaign and Donald J. Trump. Today’s politics are still mostly defined by the same issues that brought these voters to the Democrats. As long as that’s true, they may well remain by their side.

It’s possible — even likely, if Mr. Trump is the nominee — that the 2024 presidential election will be fought over issues similar to those in recent elections. If so, it could prove to be like the 2012 presidential election, a fleeting moment of political stability that allowed incremental demographic and generational shifts to seem to carry the day. It just might not last for long.