President Donald Trump and former Vice President Joe Biden agree on one thing — the other side is trying to steal the election.

Trump told a gathering of students in Phoenix that this “will be, in my opinion, the most corrupt election in the history of our country.”

The president of the United States actively undermining faith in the electoral process is gross and unprecedented, but he’s not alone.

Asked by Trevor Noah of “The Daily Show” whether he worried the election would be rendered “moot” by his supporters being prevented from voting, Biden replied: “It’s my greatest concern. My single greatest concern. This president is going to try to steal this election.”

This wasn’t an isolated comment. “Mark my words,” he warned in May, “I think he is going to try to kick back the election somehow, come up with some rationale why it can’t be held.”

Yes, if there is one thing everyone can now agree on, it’s our inability to pull off a free and fair election.

Perhaps a handy victory by Biden or, much less likely, Trump will take the edge off the postgame acrimony, but it is going to be ugly regardless. If the election is close, the aftermath will be a norm-busting extravaganza of conspiracy theories, lawsuits and, at the very least, threats to take it to the streets.

If Trump loses, there’s unlikely to be a concession phone call — one of the little grace notes of our democracy — and he will argue that he was undone by Democratic cheating. Heck, he won in 2016 and still maintained he’d been cheated.

The transition would surely be unlike any we’ve ever seen, with the incumbent routinely insulting his soon-to-be successor. Trump would be likelier to live-tweet Biden’s inauguration than to attend.

And if he wins, it could be even even worse.

There were protests in the streets after Trump won in 2016. In the supercharged atmosphere of 2020, we shouldn’t be surprised by riots. After once again believing he’d inevitably lose and facing another intolerable four years of President Trump, the left’s shock and despair would be unlike anything either side in our politics has experienced in memory.

One of the ironies of the 2016 election is that Democrats rightly scolded Trump for preparing the ground not to accept the election result. Then, when he won, they resisted accepting the result themselves, preferring to believe that the election had been stolen by Russia.

A close result will obviously magnify feelings on both sides. The Florida vote controversy of 2000 was the height of recent domestic contention over a presidential election. Looking back, though, it was remarkably tame.

With control of the presidency hanging by a thread in Florida, there were no large-scale demonstrations, let alone violence. The legal briefs flew fast and furious and both former President George W. Bush and former Vice President Al Gore wanted to win and distrusted the legal and electoral maneuvers of the other side.

Yet there were things that neither of them would say in public and both of them were willing, if it came to that, to concede with grace. Both men were shaped by the post-World War II consensus in American politics. They had absorbed its standards and reflexively honored its guardrails.

That was 20 years, and an eon ago.

Rich Lowry is editor of the National Review.