WASHINGTON — The latest surge of the coronavirus is another reminder for President Biden of how hard it is to get ahead of the pandemic.

Vaccine effectiveness has waned in the onslaught of Delta and Omicron. A spike in demand for testing is straining the system. And masks remain a political issue across the country.

Nearly a year into his presidency, Mr. Biden’s promise to “shut down the virus, not the country” remains only partly fulfilled. Stubborn resistance to vaccines among millions and the arrival of the fast-spreading new variant have upended the president’s plans for a hopeful, end-of-the-year holiday season.

Just a week before Christmas, Mr. Biden had to offer a warning of gloom.

“We are looking at a winter of severe illness and death — if you’re unvaccinated — for themselves, their families, and the hospitals they’ll soon overwhelm,” Mr. Biden said at the White House on Thursday. “The whole point is: Omicron is here, it’s going to start to spread much more rapidly in the beginning of the year, and the only real protection is to get your shots.”

Issuing dire new warnings is not where Mr. Biden or his top advisers expected they would be at this point in the year.

The plan was to overwhelm the virus with vaccines that would all but stop its spread and allow the country to fully reopen. In July, Mr. Biden went so far as to declare the nation close to “independence from a deadly virus.’’ When the Delta variant upended those plans, Mr. Biden accelerated efforts to deliver vaccinations and booster shots to as many Americans as possible.

But by the end of this week, some schools, restaurants and theaters had closed and many Americans felt they were back where they started two years ago. Mr. Biden’s health advisers did what they could to paint a brighter picture.

“Unlike last winter, we now have the power to protect ourselves,” Jeff Zients, the president’s coronavirus response coordinator, told reporters. “Our vaccines work against Omicron, especially for people who get booster shots when they are eligible.”

Rochelle Walensky, the director of the Centers for Disease Control and Prevention, said that when vaccinated people get sick from Omicron, “these cases are milder or asymptomatic.”

The reassurances have done little to help Mr. Biden politically as a pandemic now entering its third year continues to weigh on his presidency.

The third — and largest — piece of his economic agenda has stalled in Congress because of ongoing battles in his own party. Mr. Biden’s pledge to protect voting rights with legislation remains short of the votes needed for passage. And his promise to finally offer a path to citizenship for millions of undocumented immigrants was dealt another setback by the Senate parliamentarian this week.

Perhaps most ominously, Mr. Biden will enter 2022, a midterm election year, amid growing concerns about the economy, just when he hoped a receding pandemic would improve voters’ outlook. Unemployment is near record lows but rising inflation, in part because of pandemic supply chain problems and pent-up consumer demand, is driving dissatisfaction with Mr. Biden.

A recent NBC News poll showed just 37 percent of Americans approve of the president’s handling of the economy, while 56 percent disapprove. An ABC/IPSOS poll showed similar results, with more than two-thirds saying they disapprove of how the president is handling the issue of inflation.

White House officials have said repeatedly that they believe the public’s feelings about their economic plight is shaped — and soured — by the pandemic. Asked why so many people disapprove of the president’s economic policies, Jen Psaki, the White House press secretary, blamed what she called virus fatigue.

“We’re still in the middle of fighting a global pandemic, and people are sick and tired of that; we are too,” she told reporters at a recent White House briefing. “And it impacts how people are living their lives, their fear about sending their kids out the door, about going to work.”

The president’s plan for getting the nation through the winter surge includes booster shots for all adults, an expansion of at-home testing paid for by health insurance plans, tougher rules for international travel, the use of new anti-viral pills to help prevent hospitalization, and new efforts to keep schools open.

On Friday, the C.D.C. announced a new policy in which even unvaccinated students who are exposed to the virus can remain in school as long as they test negative twice in the days after the exposure. The so-called test-to-stay protocol is intended to help the nation’s schools stay open during the latest surge.

Mr. Biden is left with doubling down on the approach he has taken for most of the year: pleading with Americans to get vaccinated.

“Go get your shot today,” he said on Thursday. “Go get boosted if you’ve had your first two shots. If you haven’t, go get your first shot. It’s time. It’s time. It’s past time. And we’re going to protect our economic recovery if we do this. We’re going to keep schools and businesses open if we do this. And I want to see everyone around to enjoy that. I want to see them enjoy the fact that they’re able to be in school, that businesses are open and the holidays are coming.”

The question for Mr. Biden and his team is whether anything they are doing can help soothe the psyches of Americans as they brace for potentially more months of Zoom meetings, canceled sports games and masks.

In his Friday briefing, Mr. Zients sought to assure the public that “this is not a moment to panic, because we know how to protect people and we have to tools to do it.”

“But,” he added, “we need the American people to do their part.”