When folks talk about the political pendulum, they usually refer to the short term swings, on the order of two years. I am quite interested in the long term pendulum swings––the ones that oscillate every 40-50 years. When FDR was elected, he followed a period of conservatism––Hoover, Coolidge, Harding––and ushered in a massive sea change that would last for 48 years. The age of Roosevelt was followed by the age of Reagan, which has lasted for 40 years now. In my impatient anticipation of the end of Reaganism, I've long thought about the shape of these long term pendulum swings. I guess I really went down this rabbit hole when I realized in a crush of depression that Obama was not the Reagan-slayer I hoped he'd be. Let's look at the similar trajectories of the Roosevelt and Reagan eras.
Roosevelt and Reagan are the ones who kicked off new long term ideological trajectories.
Truman and Bush Sr. were both able to largely coast off the momentum of their predecessors despite not being terribly charismatic or popular on their own terms. But they represented a continuation of the new, popular ideology.
Eisenhower and Clinton were both presidents of the party out of ideological favor, who had rather successful terms in office hewing closer to the prevailing ideology than their own "base voters" would have preferred.
Kennedy/Johnson and Bush Jr. were administrations that seemed to reach the peak, and in retrospect the tipping point, of their respective ideologies. They both got us mired in endless land wars in Asia and left behind troubled economies. They also, while being probably the most liberal/conservative administrations of their entire cycles, were eventually rejected and erased by their own bases.
Nixon and Obama represented false endings for the ages in which they were elected. Their respective oppositions had reason to believe that these presidents were going to make a radical break with the prevailing ideology which created a burning, focused hatred in their political enemies. Ironically, if you look past their rhetoric and style, and look at their actual policies, neither of them really made much of an ideological break from their respective eras. Nixon created the EPA and Obama was the "deporter in chief" who made Romney-care the law fo the land and spent a third of the recovery act on tax cuts.
Carter and Trump (and I am NOT drawing any moral equivalence here, dear God) were each the last hurrah for their ideological ages. They both, for different reasons, left an economy in crisis. Their parties both seem to have lost the plot at that point. Carter and the Democrats really should have been able to get universal healthcare (arguably the holy grail of the liberal/progressive project) done, but infighting with Ted Kennedy pushed it off and the moment was lost for decades. Meanwhile, Trump and the Republicans dove into tariff wars and jumped into bed with an old KGB colonel.
My fervent hope in the primaries was that we could nominate Elizabeth Warren as the Democratic candidate, because I saw her as the most likely candidate to be the next tidal shift in our politics away from the age of Reagan. Biden was not in my top ten. And yet here we are. Even though the Democratic majority is razor thin, we appear as though we are shedding ourselves of the dead skin of austerity and tax cuts. We appear against all odds to be once again investing in our infrastructure. Is this really the long-awaited final nail in Reagan's coffin? Dear God, I hope so!
(Also, I'd like to acknowledge that I'm writing a particular narrative here, and ignoring some important facts. For instance, Roosevelt threw Japanese Americans in concentration camps. The Democratic Party for over half the age of Roosevelt was also the party that condoned white supremacy and southern apartheid, meaning that when Eisenhower sent the National Guard to enforce desegregation, he was angering conservatives, but those conservatives were most all Democrats, not Republicans.)