“The only garbage I see out there is his supporters,” said President Biden on Tuesday evening, referencing a comedian’s comment at  President Trump’s Madison Square Garden rally, as Vice President Harris delivered on the Ellipse, visible from the White House windows, what her campaign has described as her “closing argument” speech of her campaign.

Calling half of America’s electorate “garbage” is obviously political malpractice. Recognizing that was the White House press office and a liberal Politico reporter’s insertion of an apostrophe, joined by an apology posted on X in Biden’s name about an hour later.

However, these attempts to mislead seem unpersuasive considering the barrage of comparisons by Democrats, up to and including Ms. Harris’s running mate, Governor Walz, of the Trump rally with a 1939 Madison Square Garden rally for the pro-Nazi German American Bund. 

Actually, that rally was conducted in an earlier Madison Square Garden, demolished in 1968, while the current arena has been the site of the 1976, 1980, and 1992 Democratic National Conventions, all of which I attended.

Of course, as Axios’s Alex Thompson quickly noted, “Operatives in both parties instantly saw (Biden’s comment) as a flashback to Hillary Clinton’s ‘basket of deplorables’ comment.”

The difference is she insulted only half of Trump’s supporters, while Mr. Biden seemed to insult all of them.

Sensible Democrats understand that. Governor Shapiro, apparently surprised by a CNN interviewer’s question, replied, “I’m giving you my fresh reaction to it. I would never insult the good people of Pennsylvania or any Americans if they choose to support a candidate that I didn’t support.”

The Trump campaign instantly emailed supporters, “You are not garbage.”

Mr. Biden’s “garbage” comment, a week before Election Day, stepped all over Ms. Harris’ “closing argument,” in which she said, “I don’t believe people who disagree with me are the enemy. … I’ll give them a seat at the table.”

It hurts because it’s indicative of the contempt and hatred many Democratic politicians and voters feel for their fellow citizens who support the other party’s candidate. However, it’s not the first possibly calamitous mistake made by either side’s campaign during this closely contested campaign.

The “garbage” comment was evidently a riposte to a comedian’s joke at the Trump rally that Puerto Rico is “a floating island of garbage.” Puerto Rico actually has a landfill shortage problem, but whoever failed to vet the comedian’s text or approved it committed political malpractice.

Democrats gleefully hoped to exploit it in the only target state with many voters of Puerto Rican heritage, although polling suggested that much lower shares of Latinos than Black people take offense at arguably disparaging comments. 

Republican strategists are hoping it will augment their side’s advantage in enthusiasm, which has been reflected pretty clearly in early voting in Nevada and perhaps Arizona, Georgia, and North Carolina as well.

Beyond individual incidents, it’s arguable that both campaigns have made fundamental mistakes that will be considered fatal for whichever of them loses. 

Not just at Madison Square Garden but in one rally after another, the Trump campaign has taken the risk that invited speakers and, perhaps more likely, the candidate himself will make statements that are politically damaging or can be rendered as such by not only Democrats but a hostile press.

Trump’s disjointed sentences, in which, as he said, he “weaves” his ideas together, leave him vulnerable to malicious misinterpretation, such as the argument still peddled by Mr. Biden that he did not condemn “neo-Nazis and white nationalists” at Charlottesville in 2017.

The Harris campaign, in contrast, has been careful to subject its candidate to only a few challenging or not entirely sympathetic interviews, and even there, she has not always been prepared with politically deft responses. 

She told the women at “The View” that nothing came to mind when she was asked how she differs from Mr. Biden. Although apparently healthy and a comparatively youthful 60 years old, Ms. Harris has made fewer public appearances than any candidate in the last five campaigns except Biden in 2020.

Voting for president is a person’s most personal choice, and Ms. Harris’s strategy of cagey responses and refusal to give more than perfunctory explanations of changes from her radical 2019 campaign stances risks losing votes another Democrat might win. If Trump risks disclosing too much of himself, Harris risks disclosing too little.

These perhaps unwise risks seem pretty clearly to have been driven by the candidates, not their managers. Lesser decisions may seem unwise in retrospect — Trump campaigning in Democratic-leaning New Mexico, Ms. Harris promoting a rally with Beyonce at Houston where the singer didn’t sing, both candidates pandering with proposals such as no taxes on tips, spending and trade policies likely to trigger renewed inflation.

If Ms. Harris loses, an impaired Mr. Biden stepping down from pursuing a second term at 81 years old and then clearing the way for a largely unvetted and unpracticed Harris to replace him might seem an obvious mistake. 

If Trump loses, it might appear obvious that it was a mistake for Trump to insist he really won in 2020 and elbow aside all primary competition this year at 78 years old.

It’s tempting to conclude that Trump couldn’t beat any Democrat except Ms. Harris and that Ms. Harris couldn’t beat any Republican except Trump.

All that said, it’s unwise, less than a week away from the election, to be confident that your candidate has made their last mistake or that the opposition’s last mistake will surely be decisive.

“There’s a non-trivial chance,” wrote National Review’s Dan McLaughlin, “that the worst, stupidest & most important things to happen in this election haven’t happened yet.”

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