A new Pew Research Center report on millennials has been receiving well-deserved attention. For politics, the prevailing interpretation of the report seems to be: Republicans are screwed. Millennials are more liberal and Democratic-leaning than older generations, and because most millennials will outlive those older generations, the country’s future is largely defined by the politics of millennials. And that future, the argument goes, is bad for Republicans.

In fact, the story is much more equivocal. Lurking within this broad category of millennials is a group that isn’t quite as keen on liberalism, Democrats, or President Obama: Millennials who actually entered the electorate during the Obama presidency. These youngest millennials may yet demonstrate why it is dangerous to assume that subsequent generations will be loyal Democrats.

The reason is this: The dominant party identification of any new generation depends on the political and economic fundamentals in the country when that generation enters young adulthood. A booming economy and a popular president will push young people toward the president’s party. A recession and an unpopular president will push young people toward the opposite party. This graph from earlier research by the Pew Research Center (which I’ve noted before) shows how differently generations have voted depending who was president when they came of age:

This shows the risks in predicting that, politically speaking, the young people of tomorrow will be like the young people of today. Someone looking at young people during the Reagan-Bush years, for example, might have assumed that the Republicans’ future was bright. In fact, some did! Here is E.J. Dionne, writing on the cusp of the 1988 election:

It is said that the future belongs to the young, which gives the Republican Party a lot to look forward to.

Here is some evidence that the political views of today’s young people also depend on who was president when they entered the electorate. I draw on a large collection of YouGov polls from the 2012 election, which featured in Lynn Vavreck’s and my book on that election. The advantage of these polls is their combined sample size (45,000), which includes nearly 8,800 people who were ages 18-33 in 2012. With that large of a sample, it is much easier to see differences among young people.

Knowing that the partisan complexion of millennials should depend on the situation of the incumbent president, it is useful to compare millennials who came of age politically during one of four periods: Bill Clinton’s second term, George W. Bush’s first term, George W. Bush’s second term, and Obama’s first term. Young people should tilt most toward the Democrats if they came of age during Clinton’s second term — when the growing economy helped make him one of the most popular second-term presidents — and during George W. Bush’s second term, when his popularity plummeted amid the recession and the war in Iraq. But coming of age during Bush’s first term, which included the huge boost in popularity after 9/11, and Obama’s first term, in which he had fairly low approval numbers, should do less to push young people toward the Democrats.

In some respects, these four groups of young people aren’t different. As the Pew survey found, similar fractions (about 52 percent-55 percent) approved of Obama. But in other respects, there were differences, and they fit the expected pattern. Consider this graph:

Those who came of age during Clinton’s second term or Bush’s second term were more likely to vote for Obama, to identify with or lean toward the Democratic Party, to identify as liberal, and to agree that “it is the responsibility of the federal government to see to it that everyone has health care coverage” — relative to those who came of age during Bush’s first term or Obama’s first term. In fact, those millennials who came of age during Obama’s first term were the least likely of these four groups to vote for him or identify as Democratic.

If we zero in even further on the youngest of the millennials in these polls — those who turned 18 during Obama’s first term — the potential challenges for Democrats become even clearer. Among self-reported voters who were 18 years old in 2012, Mitt Romney, not Obama, won the majority: 57 percent. Romney also won 59 percent among 19-year-olds, and 54 percent among 20-year-olds. These youngest voters of 2012 had entered the electorate in 2010-2012, when Obama’s popularity was much lower than the high point of his inauguration. Only among “the oldest of the youngest” — 21-year-olds, whose political memories would have been forged during Obama’s first year in office and perhaps during his first presidential campaign — did Obama win a clear majority (75 percent).

Another 2012 poll suggests a similar story. This poll, by political scientists Jennifer Lawless and Richard Fox, surveyed large samples of college and high school students. Although both groups leaned toward the Obama, the high school students did so to a far lesser extent than the college students.

The data cannot tell us how these youngest millennials will end up voting as their political maturation continues. If the key experience is coming of age during Obama’s presidency, then clearly that experience isn’t over yet. Were the economy to boom and Obama’s popularity to increase, the youngest millennials probably would tilt more toward the Democrats.

Instead, the problem arises in predicting the views of future generations based on the views of millennials today. For some issues, those predictions may be accurate. At a minimum, the political identities of future generations will depend on economic trends and the popularity of presidents who haven’t been elected. Maybe those factors will tend to break in Democrats’ favor, and maybe they won’t.