But much of what afflicts Democrats seems like simple post-2016 stress disorder — a lingering trauma from the election upset that gave the U.S. Donald Trump as president.

No doubt Trump will have some advantages for the general election that could keep him in the Oval Office for another four years.

In fact, it’s conventional wisdom that Trump will win re-election. Republicans overwhelmingly believe it, as do a good number of Democrats, according to polls. More telling: incumbent presidents normally have a second term — so why not Trump?

Here is maybe why not.

These aren’t normal times. Politics is changing. There are ample signs Trump is in trouble.

Low approval rating

First, Trump is uniquely unpopular. His average approval rating in the conservative-leaning RealClearPolitics aggregate of polls is 44 per cent, and in the Fivethirtyeight aggregate it’s just 42.3 per cent.

Other presidents have scored worse, but Trump is the only president who has never had an average approval rating higher than the 46.1 per cent support he got on election day in 2016. By that measure, his re-election in the fall would be an unprecedented presidential bounce-back.

One explanation for his low approval rating is that Trump has campaigned and governed to please his base, seemingly without interest in expanding it. That’s always been a risky tactic because his base is not big enough to guarantee re-election, as we’ve seen in recent election results.

Since Trump’s win in 2016, Democrats have swarmed to the polls and overwhelmed Republicans in special elections (a Senate seat in deep-red Alabama in 2017, for example), off-year elections (formerly Republican Virginia now has a Democratic executive and legislature), and most consequentially, the 2018 midterm elections when Democrats convincingly took back the House.

Democratic voter hyper-enthusiasm is a standard feature of U.S. elections now. It’s even present in the primaries. Democrats needed only a signal to let them know which candidate to back.

So when Biden won South Carolina in a landslide, that was the signal to swarm to him a few days later on Super Tuesday. He didn’t need the most money, he didn’t need the best organization or the freshest idea, he just needed the signal that he was «the one.»

‘A basic math problem’

The lesson from all of it is that Democrats have a desperate yearning to vote Trump out hard — as they have since he was elected. Even some of the better-known #NeverTrump Republicans won’t just sit it out but will vote for whoever is the Democratic nominee — yes, including Sanders.

Trump won in 2016 because Democrats stayed home. They’re not staying home anymore.

So there is a much greater likelihood that the 2020 electorate will resemble the 2018 electorate that delivered a Democratic majority to the House than resemble the electorate that delivered Trump to the White House in 2016.

That’s according to research by the election forecaster and political scientist Rachel Bitecofer. When others were skeptical of a democratic «blue wave» in 2018, she insisted it would be big, and the stunning accuracy of her forecasting model surprised even her.

«Trump has a basic math problem,» Bitecover wrote in the New Republic last month.»There are more potential Democratic voters out there than there are Republican, and not just in California. There are more in the midwest and in the Sun Belt.»

Which gets us to electoral college math.

In 2016, Trump lost the popular vote by nearly three million votes to Hillary Clinton, but he still won the presidency in the electoral college because of narrow wins (totalling fewer than 80,000 votes) in three states: Wisconsin, Michigan, Pennsylvania.

That narrow victory along such a narrow path of states remains his best hope in 2020.

But not only are things changing within those states — Wisconsin, for instance, threw out Republican governor Scott Walker in 2018 and replaced him with a Democrat — Democrats could have new electoral college opportunities in Nevada and Arizona as well as better chances in the states Trump won by a hair four years ago. Bitecover says Florida is in play too.

Identity politics in play

Trump may have an advantage in what is said to be a relatively strong economy — even if it isn’t as good as he says it is.

In his recent book Why We’re Polarized, journalist Ezra Klein pulls together reams of data and numerous studies to show that American identity politics polarizes everything. That means voter perceptions are shaped by their political identity: If you’re a Republican, you’re likely to think the Trump economy is good; if you’re a Democrat, you’re likely to think it isn’t (the reverse was true under President Barack Obama).

There’s always the McMillan Rule, of course. Decades ago, when British Prime Minister Harold McMillan was asked by a reporter what would most likely distract his government from its intentions, he answered: «Events, dear boy, events.»

And there will be events between now and election day.

But the enduring lesson of Trump’s presidency seems to be that McMillan’s Rule has been suspended and events don’t matter anymore. Trump’s dismal approval rating is largely baked in and equally unaffected by record low unemployment and high stock market prices as by impeachment and a muddled response to a deadly virus.

Which leads us back to the importance of turnout in November. If voters aren’t as easily persuaded on issues as they once were, then what matters more is who shows up to vote.

The evidence from 2018 is that a strong Democratic turnout beats a strong Republican turnout.

It could be a close race because, thanks to gerrymandering, voting rule changes and the electoral college, Republicans don’t need as many votes as Democrats do to win congressional seats or the White House.

But if 2018 is the model, Democrats are in pretty good shape.