Democratic presidential candidate former Vice President Joe Biden speaks about the coronavirus Thursday, March 12, 2020, in Wilmington, Deleware. Credit: Matt Rourke | AP

Democrats have spent a considerable amount of time wringing their hands over the imperfections of their presidential candidates, which have become more pronounced as the field has narrowed. Now, with former Vice President Joe Biden rising phoenix-like to a commanding lead over Sen. Bernie Sanders, much of the punditry has focused on the disdain young voters hold for President Barack Obama’s aging wingman.

And it’s not just 20-somethings who view Biden like an annoying co-worker no one ever wants to grab lunch with. Some of my more progressive colleagues on the editorial board — no spring chickens are we — have a visceral dislike for Uncle Joe.

This conjures up visions of 2016, when Democrats’ lack of enthusiasm for Hillary Clinton helped Donald Trump pull off the upset of the century. To progressives, the Democratic Party appears willfully ignorant of the lessons of that campaign.

But there’s a different lesson taught every four years. Moderates argue that nominating Sanders, a self-proclaimed democratic socialist, would ignore the lessons of 1984, 1972 and 1964, when Democrats or Republicans handed the baton to candidates on the far left or right, respectively, and got their butts kicked.

The November election will have a fundamentally different dynamic from that of the 2016 contest in at least two important respects. First, this year’s vote won’t be a referendum on “the swamp,” the slow recovery from the Great Recession or any other abstraction; it will be a referendum on the incumbent, President Trump, an exceptionally divisive figure. Many progressives and young voters looked at Clinton and Trump in 2016 and saw two sides of the same coin, or so said some of the voters who sat out that election.

Now that Trump has displayed his colors on climate change, immigration, environmental protection, student loan debt, health care, the federal safety net and so many other issues, no one can reasonably see even as solidly establishment a figure as Biden as interchangeable with Trump.

And second, whoever the Democratic nominee is, he won’t be saddled with a fraction of the ill will that Hillary Clinton engendered. Neither Biden nor Sanders has been forced to endure the relentless campaign of character assassination that the Clintons did for three decades. That made Clinton much more vulnerable to the GOP attacks in 2016.

Which is not to say the Democratic nominee’s image won’t be beaten to a bloody pulp in the campaign. Trump has been working on the Bidens for a year in an attempt to elevate Sanders, whom he’d clearly prefer to face in November. And Hunter Biden’s decision to enrich himself in Ukraine while his father was trying to battle corruption there is going to make it harder for Joe Biden to capitalize on Trump’s obvious conflicts of interests and ethical failings.

Yet it’s worth remembering who the 2020 election will be about — and it’s not Biden or Sanders. We saw in 2018 that Trump is the ultimate motivator for Democrats. Sanders’ candidacy may not be inspiring masses of young progressives to cast a vote in this year’s primary, but Trump’s hold over the White House inspired a huge number of suburban women and swing voters to go to the polls in November 2018 to force Trump to split power with Democrats in the House. And the economy was in full swing then; now, the coronavirus outbreak threatens to push us back into recession.

So it may not matter how much enthusiasm Biden generates compared with Sanders at the end of the day. Trump is ginning up enough for both sides.

Jon Healey is the Los Angeles Times’ deputy editorial page editor.