In a lengthy op-ed published in The Atlantic this week, Hoover Institute senior fellow Niall Ferguson and analyst Eyck Freymann argue that freshman Rep. Alexandria Ocasio-Cortez (D-NY) is not necessarily the radical leftist she often is portrayed to be when compared with her generation.

Millennials, and Generation Z–Americans between the ages of 18 and 38, are burdened by student loan and credit card debt. They have faced stagnant wages and were hit with a financial crisis at the start of their working careers and the slow recovery that followed. Absent significant changes in fiscal policies and programs, these groups are unlikely to receive the type of entitlements current retirees receive.

For these reasons, the authors argue, these generations have been given little while much has been expected of them. Had their earlier life experiences been different, they could as easily become enamored with the cost-cutting ideas of the Republican Tea Party, had they been genuine. Instead, these young voters have shifted to the left on virtually every policy issue, cultural and fiscal alike.

While accepting the Democratic nomination in 1936, Franklin Delano Roosevelt said, “To some generations much is given. Of others much is expected. This generation of Americans has a rendezvous with destiny.”

For much of the 20th Century, historians and others engaged the idea that generation changes could explain U.S. politics.

Others wrote about “cycles of American History,” and one theory praised by Steven Bannon, former advisor to President Trump, predicted crisis and major political realignment every 80 to 90 years.

But the current authors are skeptical of these explanations. Instead, they seem to agree with Karl Mannheim, who pointed out more than 90 years ago that a generation is not solely defined by the period in which it lives, but also by the experiences shared during its early years.

In short, America may be facing a generation war, and this may be the best way to describe how and why the Democratic and Republican parties are diverging as they are. As a result, The Democratic Party is quickly becoming the party of the young, fueled by Millennials, who are born between 1981 and 1996, and Gen Z, who are born after 1996.

Meanwhile, the Republican Party is relying on retirees, particularly those born before the end of World War II in the mid-1940s.

Two other groups, Baby Boomers, born between 1946 and 1964, and Gen Xers, born between 1965 and 1980, are stuck in between, with Boomers increasingly moving to the right, and Gen Xers moving to the left.

While these developments may have little impact on presidential elections in 2020 and 2024, their effects are likely to be profound going forward. That is, if voter turnout among the younger groups adheres to historical averages. If electoral participation among younger groups were to surge, dramatic change could be felt sooner.

At the moment, older generations control all branches of government, while septuagenarians Joe Biden and Bernie Sanders are leading the current field of Democratic presidential candidates.

But the Democratic Party is moving left, evidenced by even moderate Democrats supporting Medicare for All, and many at least paying lip service to Ocasio-Cortez’s Green New Deal.

By 2039, Gen Z and Millennials will account for more than 60% of all eligible voters, so key policy reforms, such as universal health care, student loan forgiveness, immigration reform, and key features of the Green New Deal, may be tangible realities in the very near future.