Everyone knows that Barack Obama can put together a winning coalition in a presidential election. He did it twice.

What’s less clear is whether the Democratic Party and its 2016 presidential nominee will be able to build a coalition that resembles the one Obama assembled in 2008 and masterfully re-created four years later.

New data from the Census Bureau help answer that question, shining a light on two pillars of the Obama electoral foundation: African Americans and young people.

Black voters, the census study makes clear, were the story of the 2012 election. For the first time since the bureau started measuring voter participation in 1996, the African American turnout rate (66 percent of eligible voters) surpassed that of whites (64 percent). Not only that, but 1.7 million more African Americans voted in 2012 than in 2008 — even as 2 million fewer whites voted than did four years earlier.

The trend over time is even more impressive when it comes to African American participation, which has increased by 13 percentage points since 1996. (White voting rates have risen by three points during that time frame, and Hispanic voting rates have increased by four points.)

Obama’s dominance among the increasing share of black voters is well documented. He took 95 percent of the African American vote in 2008 and won 93 percent last November. While those percentages are impressive, they aren’t entirely anomalous. Then-Sen. John F. Kerry (D-Mass.) won 88 percent of black voters in 2004, and Al Gore took 90 percent in 2000. Even in the 2010 midterm elections, when Republicans were ascendant, 89 percent of black voters chose Democratic candidates.

It’s hard to imagine any future candidate garnering the sort of excitement, enthusiasm and near-unanimous support in the black community that the first African American presidential nominee was able to generate. But the numbers going back several elections suggest that it’s possible for the Democratic Party — and its next nominee — to come close.

If past is prologue, the bigger problem for the party in attempting to rebuild the Obama coalition is the youth vote.

The census study of the 2012 electorate found that just 41 percent of eligible voters ages 18 to 24 actually voted, well below the overall turnout rate of 62 percent of eligible voters. The youth voting rate was a significant dip from the 49 percent of voters ages 18 to 24 who turned out in 2008.

The drop-off continues a long-term trend as young voters’ share of the electorate shrinks. Voters ages 18 to 29, a slightly broader age group used by exit pollsters, were nearly a quarter of the electorate in 1984. Since then, their share has declined steadily. The Census Bureau survey found that voters ages 18 to 29 made up just 15 percent of the 2012 electorate — lower than exit poll data have shown for the past few elections.

That decline should be of significant concern to Democratic strategists, particularly without Obama on the ballot in future elections. Obama’s success among young voters — and this is perhaps the most misunderstood aspect of his victories — was not his ability to turn out that many more young people but rather his consolidation of their support. Obama won more than six in 10 voters ages 18 to 29 in 2008 and 2012, while Kerry and Gore won about 50 percent in 2004 and 2000, respectively. House Democrats won 55 percent of 18-to-29-year-olds in 2010.

In 2014 and 2016, then, it’s possible that young voters will not only represent a smaller share of the electorate than they did in 2008 or 2012, but also will not be as united behind Democrats as they were behind Obama.

Of course, candidates can change the equation. That is, after all, why we run the races. But the assumption that the coalition Obama built in the past two presidential elections will simply carry over to the next Democratic presidential nominee — or to the party more broadly — is far from proven.

Obama reshaped the American electorate thanks to a combination of his background, his gifts as a candidate and demographic changes in the country. And there doesn’t appear to be another Barack Obama waiting in the wings — at least at the moment.

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