President Donald Trump addresses supporters during a campaign rally at the Ocala International Airport, Friday, Oct. 16, 2020, in Ocala, Fla. Credit: Phelan M. Ebenhack / AP

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After almost four years of Donald Trump in the White House, it has become all too easy to forget how abnormal his presidency has been — how many norms he has trampled, how many rules he has broken.

But the final stage of Trump’s reelection campaign is bringing all the strands of Trumpism to an unhinged crescendo.

In the last three weeks, the president has:

Publicly urged Attorney General William Barr to prosecute his Democratic opponent, Joe Biden, and former President Barack Obama for purportedly spying on Trump’s 2016 campaign, although no evidence suggests they committed a crime. “These people should be indicted,” Trump said. “That includes Obama, and it includes Biden.”

Renewed his false claim that Democrats have rigged the presidential election.

Warned his followers that if Biden wins, Republicans might never win another election. “They want to turn America into communist Cuba,” Trump told a rally Monday in Florida.

Refused to commit to a peaceful transfer of power if he loses. “We’ll have to see,” he told reporters. “There won’t be a transfer, frankly. There’ll be a continuation.”

This is, to put it mildly, not normal.

Previous presidents often warned of dire consequences if their opponents were elected, but they didn’t accuse their political foes of treason or of trying to end the American way of life.

During Watergate, President Richard Nixon pressed the FBI and the Internal Revenue Service to investigate his critics, but he made the demands in secret, presumably because he knew it was wrong.

No U.S. president has previously suggested that he might not accept the results of an election.

Trump hasn’t succeeded in seizing the powers of an autocrat, but he often sounds like he’d like to.

Even Barr, who believes in a broad definition of presidential powers, has pushed back against Trump’s attempts to dictate whom he prosecutes.

But Trump’s style and strategy are still doing serious damage to American politics.

He’s deliberately feeding partisan polarization, the animosity that drives Americans in both parties to view those on the other side as enemies — instead of merely neighbors with mistaken ideas. In the worst case, it could even inspire violence — as it almost did, apparently, when a group of men allegedly plotted to kidnap Michigan Gov. Gretchen Whitmer, a frequent target of criticism from Trump. Asked about the incident, the president said vaguely that he opposes violence from both right and left — and added that he thinks Whitmer “has done a terrible job.”

The tendency for Democrats and Republicans to distrust and fear each other — a phenomenon political scientists call ” affective polarization” — took root long before Trump ran for president.

In 2016, the Pew Research Center found that 45 percent of Republicans viewed Democratic policies as a “threat” to the nation; 41 percent of Democrats said the same thing about the GOP.

A 2019 Pew poll found that 55 percent of Republicans say Democrats are “more immoral” than other Americans; 47 percent of Democrats feel the same way about Republicans.

Previous presidents have used polarization as part of reelection strategies, of course.

In 2004, President George W. Bush’s campaign focused on maximizing Republican turnout and discrediting his Democratic opponent, John F. Kerry. In 2012, Obama focused on the Democratic base and discrediting his opponent, Mitt Romney.

But they treated polarization as a necessary evil, not a guiding principle. Trump has made it a centerpiece of his presidency.

He has frequently described the nation as divided between well-run Republican “red states” and poorly run Democratic “blue states” and has threatened to withhold federal aid from Democratic governors whose policies he dislikes.

“Outside of poorly run Democrat states and cities, you don’t have crime in this country,” he said Monday — an assertion that is wildly untrue.

Last month, he even claimed that the coronavirus was mainly a Democratic problem.

“If you take the blue states out … we’re really at a very low level,” he said. That statement was also wildly untrue.

Trump doesn’t merely criticize Democrats for their policies. He has falsely charged that a Biden presidency would “destroy the American way of life.” He has falsely claimed that Biden, a practicing Catholic, is “against God.”

“We got to vote these people into oblivion,” he urged supporters at the White House. “Got to get rid of them.”

Political scholars normally see that kind of demonizing rhetoric in other countries.

“We’re seeing attitudes here that are familiar from places like Venezuela, Turkey or Hungary,” Jennifer McCoy, a professor at Georgia State University who has studied those countries, told me.

“When more people are saying they see the other party as a threat to the nation, or that they are afraid of the other party, polarization has gotten pretty serious,” she said. “When one group views the other as a threat, they’re much more willing to accept undemocratic moves by their side — because they want their guy to stay in power.”

Is there a way back? Yes, but it won’t be easy.

“A leader can choose depolarization as a strategy,” she said. “Don’t engage in retribution or vilification of the other side … . Guarantee that you’ll govern for all.”

Sounds more like Biden than Trump. But first, he needs to get elected.

Doyle McManus is a columnist for the Los Angeles Times.