WASHINGTON — President Joe Biden is mired in the most devastating month of his tenure in office - struggling to contain a deadly crisis in Afghanistan, an unyielding pandemic and other setbacks that have sent waves of anger and worry through his party as his poll numbers decline.

August started with Democrats sounding quiet alarms about the resurgence of the coronavirus and the uncertain fate of Biden's domestic priorities, tempered by some optimism about the economy and a bipartisan infrastructure deal.

But the month nears its conclusion with sirens blaring about Biden's strategy in Afghanistan, where 13 Americans were killed this past week, as well as heightening concern about covid-19. These anxieties have set off a fresh round of intraparty finger-pointing.

Many Democrats increasingly fear that the tenets of Biden's presidency - competence, calm and control - can credibly be called into question for the first time, potentially laying a foundation for devastating consequences in the 2022 midterm elections.

"I just worry about his ability to achieve his agenda," said John Jackson, the chairman of the DeKalb County Democrats in Georgia, a midterm battleground.

"I don't necessarily disagree with a lot of his policies - it's his execution," added Jackson, a Marine veteran who feels Biden's handling of Afghanistan dented his competency credentials.

Democrats are defending a narrow majority in the House and the Senate. The president's party historically tends to struggle in their first midterms, spurring nervousness that escalated sharply this month. A Democratic member of the House, speaking on the condition of anonymity out of fear of retribution, said many in the caucus believe the lower chamber of Congress is already lost in the midterms. Other Democrats said they are bracing for the prospect of Republicans making double-digit seat gains.

"Up until the point of Afghanistan, people were very impressed by the organization and seriousness and maturity of the Biden presidency and its administration," said Rep. Jamie B. Raskin, D-Md. "Whether it fundamentally tarnishes that or not, remains to be seen."

In private discussions, some House Democrats have raised the prospect of whether Secretary of State Antony Blinken and national security adviser Jake Sullivan - two of Biden's most trusted aides - should lose their jobs, according to the Democratic House member and another Democrat with knowledge of the conversations, who spoke on the condition of anonymity to describe sensitive talks.

White House officials said the tumultuous month has not deterred their overarching strategy. They see positive developments on the horizon if they can weather the storm over Afghanistan, such as the prospect of signing legislation making historic investments in roads, bridges and social programs. They argue that Biden's decision to withdraw from Afghanistan was the right thing to do, despite the complications that ensued.

"I reject the idea that the president's handling of a difficult situation has somehow undermined people's sense of his confidence," said White House communications director Kate Bedingfield. "It's showing people that he can lead at a difficult time, and that he has a steady hand and that he's committed to transparency."

She added, "No president can prevent bad things from happening on their watch. The test of leadership is what you do when a bad thing happens. And I think the American people have seen him move quickly and consistently over the last couple of weeks."

Some party leaders are trying to quell worry about Biden's political standing with sharp warnings to the rank-and-file.

"Stop bed-wetting and get back to work," said Democratic Congressional Campaign Committee Chairman Sean Patrick Maloney, D-N.Y., who predicted that the party would retain its House majority in the midterms. "We're going to deliver results for the American people."

Still, Biden's allies acknowledged that he is going through the toughest test of his presidency so far. After a relatively steady first six months on the job, the upheaval of August has thrust him onto entirely different terrain.

"It's like he's gone through a big storm and he's appearing in the midst of it on a stage," said Rep. Andy Levin, D-Mich. "So his hair is jostled and his suit is affected but he's standing there steadfastly managing as best he can."

August has historically been a challenging month for presidents, and White House chief of staff Ron Klain wanted personnel to rest up and plan accordingly, according to a White House official. Staff were encouraged to take a week off, but to make sure their duties were covered. Biden and many of his top aides had long-planned vacations that they were ultimately forced to scrap.

Public polling shows fresh signs of concern for Democrats. Gallup found Biden's approval rating declining from 56% in June to 50% in July and 49% in the first half of August. A mid-August NBC News survey found pegged it at 49%, with 48% disapproving. The survey showed a 16-point drop in Biden's handling of the pandemic and Americans disapproving of his handling of Afghanistan by more than 2-to-1.

Democrats had already begun August with rising concerns about the surging delta variant, which threatened to undercut support for Biden on his signature promise to get control of the pandemic. A midsummer vaccination goal that went unmet, coupled with a renewed calls to mask up in certain settings, left some Democrats feeling like they had taken a step backward. Many also felt uneasy about stalled legislation on voting rights and police reform.

Then Biden had two notable successes: a booming jobs report and passage of the bipartisan infrastructure bill. Neera Tanden, a senior adviser in the White House, had developed a month-long plan to sell the president's agenda, which included a slew of trips by Cabinet officials around the country.

Biden bragged about his legislative triumph at an Aug. 10 news conference shortly after the bill passed, repeatedly crowing about those who doubted he could strike a deal with Republicans.

During that same news conference, Biden was also asked about the U.S. withdrawal from Afghanistan, which he had announced in the spring: With the Taliban seizing multiple cities in the span of days, would he change his plan?

"No," Biden responded. "Afghan leaders have to come together," he said. "They've got to fight for themselves, fight for their nation."

Instead, they folded, and Kabul fell to the Taliban five days later, creating a full-blown crisis in Afghanistan and a political calamity back home.

The Taliban takeover stunned Biden administration officials, who went into overdrive trying to salvage the end of a two-decade U.S. operation in Afghanistan. They focused on getting Americans out of the country.

But the administration's worst fears were realized Thursday when at least 13 Americans were killed in an attack Biden said was carried out by the terrorist group ISIS-K. The president vowed to hunt down the perpetrators and make them pay, and the Pentagon announced late Friday that an ISIS-K planner had been killed by a U.S. drone strike.

That was little comfort to many Democrats who felt he had badly botched the withdrawal and evacuation efforts, undercutting his credibility as a steady hand and seasoned leader at the same time.

"What hurts" about the attack, said Jackson, the DeKalb County Democratic chairman, is that Biden justified his withdrawal from Afghanistan in large measure "because he doesn't want American lives lost," which is precisely what happened. With all his experience, Jackson said, "Biden should have known better."

Many Democrats also fear it will fuel GOP criticism. Republicans have been laying a foundation for a midterm argument rooted in casting Biden as a weak leader who has lost control of a swirl of crises, from the surge in migrants at the southern border to a rise in violent crime and now the situation in Afghanistan.

"The United States and our allies are less safe because of this president's failures," said Republican National Committee communications director Danielle Alvarez in a statement following the deadly attack in Afghanistan. "The American people deserve leadership and strength from their leader."

White House officials reject the notion that they and the president were unprepared. "Many people who work here have lived through August before," said White House press secretary Jen Psaki. "You don't always know what the challenges are going to look like, but you know they will come."

As the summer draws to a close, some Democrats see an unexpected realignment underway in the party. Centrist Democrats, who were Biden's base when he ran for president, have emerged as some of the loudest critics of Biden's Afghanistan strategy - and a bloc of moderates nearly derailed plans to advance his economic agenda. Many liberal Democrats, who have long pressed for a troop withdrawal and are heartened by some of Biden's domestic priorities, have rallied behind him.

"The irony is that the people who have had the president's back the most in the House are the progressives," said Rep. Ro Khanna, D-Calif., a Congressional Progressive Caucus member who has defended Biden on Afghanistan.

Rep. Susan Wild, D-Pa., seen as potentially vulnerable in the midterms, said the Afghanistan evacuation process was "egregiously mishandled" even as she supported Biden's decision to withdraw troops from the country. Wild said she has an obligation to conduct oversight and wants answers to why the mission went "so badly" and was "so poorly executed."

But Wild is more optimistic about the political implications, voicing confidence that Democrats will keep their House majority in the midterms on the strength of Biden's domestic agenda. "There is no overwhelming sense of doom among Democratic front-liners," she said, referring to the most at-risk members of the caucus.

Still, many other Democrats remain anxious about holding the House. Rep. Jake Auchincloss, D-Mass., a Marine veteran who has emerged as a top defender of the White House strategy on Afghanistan, said the party faces challenging odds.

"Democrats are clear-eyed that the '22 midterms are going to be tough," he said. "We've got the historical precedent of midterms for a first-term president provoking a backlash."

Perhaps most troubling, Biden allies said, are surveys showing a drop in Americans' approval of how he is handling the pandemic. One of Biden's most salient arguments as a candidate was that he could bring the United States back to normalcy after the deadly coronavirus crisis.

That pitch is being undercut by many Americans' refusal to get vaccinated and the spread of the highly contagious delta variant, which has sent covid-19 cases skyrocketing.

"It's a tough month," said Celinda Lake, a Democratic pollster who advised Biden's presidential campaign. "It's a tough month for the country. It's a tough month for the president."

Still, Lake argued that Biden has a large reserve of trust among Americans for his handling of the pandemic. And despite its resurgence, she said her research has found that more people blame the unvaccinated and Republican governors who have worked against public health recommendations than the Biden administration.

White House officials played down the significance of polling and political trends so far in advance of the next election. "The midterms are 14 months away. They are going to play the World Series twice between now and when people vote in November of 2022," Bedingfield said.

But other Democrats are less convinced. They see the calls to mask up again as visible and symbolic reminders of a pandemic that continues to plague the country, even after Biden's much-hyped July 4 speech about the country zeroing in on declaring independence from the coronavirus.

The policies themselves are only part of the political puzzle. Democratic officials said the party will need to dramatically improve its efforts at selling its accomplishments in the fall. Some said Republicans are often more skilled at taking credit for their policies, and they cannot afford to slip up after a tough summer.

"Donald Trump spent his four years investing in billionaires and corporations and continuing to fund the forever wars," said Sen. Chris Murphy (D-Conn.). "Joe Biden thus far has spent his first eight months bringing the forever wars to a close and making historic investments in regular people. That's a story that wins, but I don't know we've done a good enough job yet of telling it."

The Washington Post's Scott Clement contributed to this report.