As he debated with himself whether to enter the race for the 2020 Democratic nomination, Joe Biden knew he had a problem.

As a senator from Delaware in the ’70s, he had bashed busing to achieve racial balance in public schools as stupid and racist.

As chairman of Senate Judiciary in the hearings on the nomination of Clarence Thomas in 1991, Biden had been dismissive of the charges by Anita Hill that the future justice had sexually harassed her.

In 1994, Biden had steered to passage a tough anti-crime bill that led to a dramatic increase in the prison population.

Crime went down as U.S. prisons filled up, but Biden’s bill came to be seen by many African-Americans as discriminatory.

What to do? Acting on the adage that your best defense is a good offense, Biden decided to tear into President Donald Trump — for giving aid and comfort to white racists.

His announcement video began with footage of the 2017 white supremacist rally in Charlottesville, highlighting Trump’s remark, after the brawl that left a female protester dead, that there were “very fine people on both sides.”

“With those words,” said Biden, “the president of the United States assigned a moral equivalence between those spreading hate and those with the courage to stand against it. And in that moment, I realized that the threat to this nation was unlike any I had seen in my lifetime.”

Cut it out, Joe. This is just not credible. Even he cannot believe Trump had in mind the neo-Nazis and Klansman chanting, “Jews will not replace us!” when Trump said there were “fine people” on both sides.

If this were truly a road-to-Damascus moment for Biden, calling forth a new resolve to remove so morally obtuse a resident of the Oval Office, why did he have to agonize so long before getting in the race?

And was Charlottesville, a riot involving Klansmen, neo-Nazis and radicals, really a “threat to this nation” unlike any Biden had seen in a lifetime that covers the Cuban missile crisis, Vietnam, the riots in 100 cities after Martin Luther King’s assassination and Sept. 11?

Even the anti-Trump media seemed skeptical. Their first interviews after Biden’s announcement were not about Charlottesville but why it took so long to call Anita Hill to apologize.

Yet there is an unstated message in the Biden video. It is this:

With the economy firing on all eight cylinders, and the drive for impeachment losing steam, a new strategy is emerging — to take Trump down by stuffing him in a box with white supremacists.

The strategy is not original. It was tried, but backfired on Hillary Clinton when she called Trump supporters “deplorables … racist, sexist, homophobic, xenophobic, Islamophobic … bigots.”

This didn’t sit well with some white folks in Wisconsin, Michigan and Middle Pennsylvania.

Yet the never-Trumpers seem to think it could work this time.

After Saturday’s attack on the Passover service in Poway, California, which took a woman’s life, Trump denounced the atrocity, expressed his condolences, called Rabbi Yisroel Goldstein, who had been wounded, and consoled him for 15 minutes.

“Nevertheless,” wrote The Washington Post Monday in a front-page headline, “President’s words push race to fore of campaign.”

“The rise of white nationalist violence during Trump’s tenure is emerging as an issue,” said the Post, because Trump “previously played down the threat posed by white nationalism (and) … also has a long history of anti-Muslim remarks.”

The article should be taken seriously. For the Post is not only an enemy of Trump but a powerful institutional ally of the left. And during presidential campaigns, it doubles as an oppo research and attack arm of the Democratic Party.

“Violence, Hate Crimes Emerge as 2020 Issues” declared the inside headline on the Post story. The Post is not talking about customary crimes of violence in America or D.C. — robbery, rape, assault, battery, murder — a disproportionate share of which are committed by minorities of color.

The crimes that interest the Post are those committed by white males against minorities, which can be used to flesh out the picture of America that preexists in the mind of the left, if not in the real world.

On Monday, Rev. Al Sharpton met with “Mayor Pete” Buttigieg. Subject of discussion: Reparations for slavery, which ended more than a century before the mayor was born.

“All is race,” wrote Disraeli in his novel “Tancred.” “There is no other truth.”