Less than a month ago, California Gov. Gavin Newsom (D) made an announcement he had been waiting a long time to make: The state was ready to put its coronavirus restrictions behind it.

“With nearly 40 million vaccines administered and among the lowest case rates in the nation,” he said on June 11, “we are lifting the orders that impact Californians on a day-to-day basis while remaining vigilant to protect public health and safety as the pandemic persists.”

Among the changes was a scaling back of the state’s mandate to allow those who had been fully vaccinated against the virus to ditch mask-wearing. This constituted an unquestionable political win for Newsom, who faces a recall in September. The state’s coronavirus-related constraints were a central theme in the recall effort, so it was useful for Newsom to be able to rescind them.

But then cracks emerged. Over the past two weeks, the seven-day average of new cases has increased by 43 percent in the state. On Tuesday, the state Capitol itself reintroduced a mask mandate following a cluster of new coronavirus infections. That change affects only a small percentage of the state, but is symbolically potent for the progress of the pandemic.

Part of the problem, clearly, is the emergence of the more-virulent delta variant of the virus. The federal government announced this week that the variant, which was first detected in India, is now the most common variation of the virus in new infections. Data from the Centers for Disease Control and Prevention shows that it is not uniformly spread around the country, however. It estimates that the region including California, Region 9, is seeing about 57 percent of new infections from the delta variant, compared with about 31 percent in Region 3, which includes D.C., Virginia and Maryland.

The regions where the virus is most common are in the middle of the country: Region 7, where 80 percent of new infections are from the delta variant, and Region 8, where three-quarters are. That’s the swath of states from Montana down to Missouri.

In both of those regions, the number of new infections is also increasing. Data from The Washington Post shows a 40 percent increase in new cases relative to population over the last two weeks in Region 7 and an increase of 10 percent in Region 8. Other regions, like California’s Region 9, have also seen increases over that period, and the increase nationally has exceeded 20 percent.

There is a correlation here. Places with a bigger increase in case totals tend to be ones where the delta variant is more common.

There’s a less clear link between the emergence of the delta variant and vaccination rates, indicated by the color of the points on the graph above. The three most vaccinated regions, though, have seen an average increase in new cases over the past two weeks of 10 percent, compared with a 30 percent increase in the least-vaccinated regions. In the least vaccinated regions, the delta variant makes up an average of 71 percent of new infections, compared to 41 percent in the most-vaccinated areas. In the least-vaccinated areas, the average number of new cases per person at this point is almost three times the rate in the most-vaccinated areas.

So far, given the available data, it’s not clear exactly how the balance of vaccinations and variants is affecting the numbers. But there is abundant evidence both that vaccination helps stem new infections, including from the more contagious delta variant, and that those most at risk of infection and serious health complications are the unvaccinated. The government’s effort to vaccinate more Americans has nonetheless met with resistance, often in places with more conservative politics.

In Missouri, for example, the federal government has dispatched a “surge response team” aimed at helping control the spread of the delta variant as it batters the southwestern part of the state. The state’s Republican governor, though, has publicly rejected the federal government’s proposal to go door-to-door to offer inoculations.

There’s even a partisan divide on concern about the variant. A Washington Post-ABC News poll conducted last month found that most Republicans think officials are exaggerating the risk of the delta variant, a view also held by most of those who don’t plan on being vaccinated. (Those groups — Republicans and the unvaccinated — overlap significantly.)

This has long been part of the problem: The Americans who are least likely to take preventive measures against the virus are also those who are least worried about it, and vice versa. Often, those Americans are Republicans.

Some Republican officials like Rep. Marjorie Taylor Greene (Ga.) go further, suggesting that delta variant concern is being overstated for political purposes.

“No one cares about the Delta Variant or any other variant,” she wrote on Twitter this week. “They are over covid & there is no amount of fear based screaming from the media that will ever force Americans to shut down again.”

“Forced masks and vaccines will cause Dems to lose big,” she added. “All voters are over covid.”

Her point about no one caring about the variant is untrue. But she is correct that few Americans are likely to embrace a reintroduction of mitigation efforts aimed at containing the virus, even if warranted by the new strain. Or warranted by other new strains of the virus — a possibility that increases as the virus continues to spread.

President Biden’s approval rating is healthy, bolstered by positive views of his response to the pandemic. If the country starts moving backward, it will likely shift how people view his presidency. In California, a reversion to stricter containment will likely shift Newsom’s position in the recall fight.

Unfortunately for Democratic officials, the people they need to persuade to get vaccinated to avoid that political fate are often people who are happy to see them suffer it.