WASHINGTON — In the past six months, cloth face masks have emerged as the simplest, cheapest and most effective weapon that most ordinary Americans can wield against the coronavirus.

Public health officials had initially warned the public against using masks — they worried that people would buy up medical-grade masks, whose supplies were limited. But in April, officials began recommending cloth face masks — which could easily be made or purchased — and now the nation’s medical experts are all but twirling signboards while break dancing in chicken costumes to get you to mask up.

Robert Redfield, the director of the Centers for Disease Control and Prevention, told a Senate panel this month that face masks might offer greater protection against the virus than a vaccine. If just about every American wore a mask over a period of six to 12 weeks, he said, “We’d bring this pandemic under control” — repeating a claim he first made in July.

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In the abstract, then, a federal plan aimed at getting all Americans to wear masks sounds like just the sort of magic fix for the virus that President Donald Trump has been fumbling for from the beginning. Yet the president has refused to impose a national mandate ordering people to wear masks indoors, nor has he proposed any other policy for achieving universal masking. Although he says he is for masks, he has frequently mocked them as wimpy accouterments of politically correct virtue signalers, and suggested that they pose many serious, though vague, dangers.

The contradictions have never been more stark than this past week. On Tuesday night, at the presidential debate, Trump first said, “I think masks are OK” and then mocked Joe Biden for his diligent mask wearing at events with other people. “He could be speaking 200 feet away from them, and he shows up with the biggest mask I’ve ever seen.” On Friday, Trump revealed that he and the first lady have tested positive for the coronavirus.

Among Trump’s various missteps in combating the virus, it is his position on masks that puzzles and infuriates me most. Why hadn’t he pushed this one, simple tool to help fix the worst crisis of his presidency?

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I worked with my Times colleagues to analyze the president’s statements on masks over the course of the pandemic. We sought to track how Trump helped to transform masks from objects as culturally benign as hand sanitizer or latex gloves into a flash point in the culture wars.

What we’ve come up with is an illustration of a tremendous missed opportunity — a zigzagging map charting not just a profound dereliction of public health, but also one of basic political strategy.

The most striking feature of Trump’s stance on masks is that it was never consistent. Trump was for masks before he was against masks before he was for them before he was against them. His attitude could best be described as existing in a kind of quantum superposition that covers all possible positions at once.

When asked about masks by a voter at an ABC News Town Hall earlier this month, he began by noting that he sometimes wears masks, then criticized Biden (who is not the president) for not issuing a national mask mandate, pointed out that health officials reversed their policy on masks, and finished up with a detour about the problem of masks worn by careless waiters.

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“The concept of a mask is good,” he concluded, “but it also does — you’re constantly touching it. You’re touching your face. You’re touching plates. There are people that don’t think masks are good.”

Trump’s random walk down the policy spectrum stands in stark contrast to other U.S. leaders and public health organizations.

Biden, for instance, has moved straightforwardly: He has gone from neutral to strongly in favor of masks.

U.S. health agencies, including the CDC, have followed the same path, going from advising in March that the general public did not need to wear masks, except for caregivers, to strongly recommending them by the summer. The World Health Organization moved much more slowly, but even that lethargic body now favors cloth masks for people who live in areas of widespread transmission, especially in settings where physical distancing is difficult.

When I look at Trump’s timeline on mask policy, I see only missed opportunity.

Early in April, when the CDC and many state health authorities began recommending that people wear masks, the public appeared broadly in favor. At the time, Trump had begun criticizing state lockdowns, but he hadn’t said much about masks, except that he probably wouldn’t wear one.

Then, at the end of April, the White House’s tone began to shift. Mike Pence was conspicuously maskless on a visit to the Mayo Clinic in Minnesota, apparently in violation of the hospital’s policy.

Mask resistors became violent; in Flint, Michigan, a Family Dollar security guard was shot and killed after telling a customer to put a mask on her child — the first of many shootings arising out of disputes about masks and other coronavirus restrictions. Trump could have tried to calm tensions. Instead he sniffed the shifting winds and leapt onto the anti-mask wagon.

His own masklessness seemed to become a point of pride. The White House instituted a mask requirement for all employees — except Trump. On a tour of a Ford factory, Trump wore a mask when he was out of view of cameras, but he took it off in public, explaining that he “didn’t want to give the press the pleasure of seeing it.” He retweeted a post from a Fox News analyst that appeared to mock how Biden looked in a mask. And when a reporter declined to remove his mask when asking a question at a news conference, Trump called the man “politically correct.”

By late spring, masks had become an irredeemably partisan issue. The primary resistors were Republican men. In a poll conducted in May by the Kaiser Family Foundation, Democrats were almost twice as likely as Republicans to say they wore masks regularly. Only half of Republican men said they wore a mask most of the time they left the house; only 43% said Trump should wear a mask.

I can’t blame Trump alone for this particular descent into the salad spinner of polarization. Robert Kahn, a professor at the University of St. Thomas’s law school who has studied the legal and cultural attitudes toward masks, has written that it was probably inevitable that masks would come to be seen as costumes that signify personal qualities rather than as neutral objects, like umbrellas. Face masks, even more than clothing, alter our bodies and our communication in a way that can’t be hidden. They are symbols as much as tools, Kahn argues.

Still, once Trump staked out an anti-mask position, much of right-wing media took their cues from him. The mask became a fault line.

In The Federalist, David Marcus argued that masks symbolized weakness. If Trump wore a mask in public, it would signal that “the United States is so powerless against this invisible enemy sprung from China that even its president must cower behind a mask.” At Trump rallies, people reveled in their masklessness, telling reporters that masks were useless, that the coronavirus was not even a serious threat, and that mask rules were an attempt by “people in power who want to see what people will submit to,” as a Trump supporter in Kansas told the BBC.

People on the left attached their own meanings to masks. A common argument was that Trump’s reluctance to wear a mask was itself a sign of weakness — of “fragile masculinity,” as journalist Liz Plank put it.

A few Republican leaders tried to shake off all this symbolic weight. Wearing a mask “is not about politics,” said Mike DeWine, the Republican governor of Ohio. Doug Burgum, the Republican governor of North Dakota, called the mask debate “a senseless dividing line,” adding, “I would ask people to try to dial up your empathy and your understanding.”

But there was no going back. Masklessness had become part of the Trump lifestyle brand. If you want the full MAGA experience, you wear the hat but not the mask.

“I absolutely think Trump made a difference,” Kahn told me. If Trump had struck a more positive tone on masks — if he hadn’t always implied they were unmanly or undignified — there might still have been some resistance to wearing masks, Kahn said, “but it would have been much less controversial.”

Compared to other countries, mask usage in the United States is in the middle of the pack; we are better than Canada, Britain and Scandinavia, but worse than Germany, Italy, Mexico and much of Asia. Usage is rising — in a Pew survey taken in August, 85% of adults said they regularly wore a mask, compared to 65% in June. But that is still short of the threshold that officials have been aiming for — 95% or more. Even if it’s quite late, a full-throated Trump endorsement of masks could still make a difference.

Continuing on the same confused path would be indefensible.