WASHINGTON — With the White House legislative agenda in shambles less than a year before the midterm elections, Democrats are sounding alarms that their party could face even deeper losses than anticipated without a major shift in strategy led by the president.

The frustrations span the spectrum from those of the party’s liberal wing, which feels deflated by the failure to enact a bold agenda, to the concerns of moderates, who are worried about losing suburban swing voters and had believed Democratic victories would usher a return to normalcy after last year’s upheaval.

Democrats already anticipated a difficult midterm climate, given that the party in power historically loses seats during a president’s first term. But the party’s struggle to act on its biggest legislative priorities has rattled lawmakers and strategists, who fear their candidates will be left combating the perception that Democrats failed to deliver on President Biden’s central campaign promise of rebooting a broken Washington.

“I think millions of Americans have become very demoralized — they’re asking, what do the Democrats stand for?” said Senator Bernie Sanders, the Vermont independent in charge of the Senate Budget Committee. In a lengthy interview, he added, “Clearly, the current strategy is failing and we need a major course correction.”

Representative Tim Ryan, a Democrat from a blue-collar Ohio district who is running for the state’s open Senate seat, said his party isn’t addressing voter anxieties about school closures, the pandemic and economic security. He faulted the Biden administration, not just for failing to pass its domestic agenda but also for a lack of clear public health guidance around issues like masking and testing.

“It seems like the Democrats can’t get out of their own way,” he said. “The Democrats have got to do a better job of being clear on what they’re trying to do.”

The complaints capped one of the worst weeks of the Biden presidency, with the White House facing the looming failure of voting rights legislation, the defeat of their vaccine-or-testing mandate for large employers at the Supreme Court, inflation rising to a 40-year high and friction with Russia over aggression toward Ukraine. Meanwhile, Mr. Biden’s top domestic priority — a sprawling $2.2 trillion spending, climate and tax policy plan — remains stalled, not just because of Republicans, but also opposition from a centrist Democrat.

“I’m sure they’re frustrated — I am,” said Senator Richard J. Durbin of Illinois, the No. 2 Senate Democrat, when asked this week about the chamber’s inability to act on Mr. Biden’s agenda. Discussing the impact on voters ahead of the midterm elections, he added, “It depends on who they blame for it.”

The end of the week provided another painful marker for Democrats: Friday was the first time since July that millions of American families with children did not receive a monthly child benefit, a payment established as part of the $1.9 trillion pandemic relief plan that Democrats muscled through in March without any Republican support.

Plans to extend the expiration date for the payments, which helped keep millions of children out of poverty, were stymied with the collapse of negotiations over the sprawling domestic policy plan. And additional pandemic-related provisions will expire before the end of the year without congressional action.

“That’s just about as straightforward as it gets,” said Mr. Ryan. “If the Democrats can’t get on with a tax cut for working families, what are we for?”

In recent days, Mr. Biden has faced a wave of rising anger from traditional party supporters. Members of some civil rights groups boycotted his voting rights speech in Atlanta to express their disappointment with his push on the issue, while others, including Stacey Abrams, who is running for governor in Georgia, were noticeably absent. Mr. Biden vowed to make a new forceful push for voting right protections, only to see it fizzle the next day.

And last week, six of Mr. Biden’s former public health advisers went public with their criticisms of his handling of the pandemic, calling on the White House to adopt a strategy geared to the “new normal” of living with the virus indefinitely. Others have called for the firing of Jeffrey Zients, who leads the White House pandemic response team.

“There does not seem to be an appreciation for the urgency of the moment,” said Tré Easton, a senior adviser for Battle Born Collective, a progressive group that is pushing for overturning the filibuster to enable Democrats to pass a series of their priorities. “It’s sort of, ‘OK, what comes next?’ Is there something that’s going to happen where voters can say, yes, my life is appreciatively more stable than it was two years ago.”

White House officials and Democrats insist that their agenda is far from dead and that discussions continue with key lawmakers to pass the bulk of Mr. Biden’s domestic plans. Talks over an omnibus package to keep the government open beyond Feb. 18 have quietly resumed, and states are beginning to receive funds from the $1 trillion infrastructure law.

“I guess the truth is an agenda doesn’t wrap up in one year,” said Jen Psaki, the White House press secretary.

While there’s widespread agreement around the electoral peril that the party faces, there’s little consensus over who, exactly, is to blame. Liberals have been particularly scathing in their critique of two centrist senators, Joe Manchin III of West Virginia and Kyrsten Sinema of Arizona, and their longstanding objections to undermining the Senate filibuster, as well as Mr. Manchin’s decision to abruptly reject the $2.2 trillion spending plan last month. For months, Democratic lawmakers, activists and officials have been raising concerns about sinking support among crucial segments of the party’s coalition — Black, female, young and Latino voters — ratings many worry could drop further without action on issues like voting rights, climate change, abortion rights and paid family leave.

“In my view, we are not going to win the elections in 2022 unless our base is energized and ordinary people understand what we are fighting for, and how we are different than the Republicans,” Mr. Sanders said. “That’s not the case now.”

But many in the party concede that the realities of their narrow congressional majorities and united Republican opposition have blocked their ability to pass much of their agenda. Some have faulted party leaders for catering to progressives’ ambitions, without the votes to execute.

“Leadership set out with a failed strategy, and while I guess, maybe they can message that they tried, it actually isn’t going to yield real laws,” said Representative Stephanie Murphy, a Florida centrist, who is retiring but has signaled aspirations for a future Senate run.

Representative Cheri Bustos, a Democrat from rural Illinois, said Democrats should consider less ambitious bills that could draw some Republican support to give the party accomplishments it can claim in the midterm elections.

“We really kind of need to reset at this point,” said Ms. Bustos, who is retiring from a district that swung to Donald J. Trump in 2020. “I hope we focus on what we can get done and then focus like crazy on selling it.”

Mr. Biden effectively staked his presidency on the belief that voters would reward his party for steering the country out of a deadly pandemic and into economic prosperity. But even after a year that produced record job growth, widely available vaccines and stock market highs, Mr. Biden has not begun to deliver a message of success nor focused on promoting his legislative victories.

Many Democrats say they need to do more to sell their accomplishments or risk watching the midterms go the way of the off-year elections, when many in the party were surprised by the intensity of the backlash against them in races in Virginia, New Jersey and New York.

“We need to get into the business of promotion and selling and out of the business of moaning and groaning,” said Bradley Beychok, the president of American Bridge, a Democratic super PAC.

Others say that as president, Mr. Biden has fallen out of step with many voters by focusing on issues like climate change and voting rights. While crucial for the country, those topics aren’t topping the list of concerns for many voters still trying to navigate the uncertainties of a pandemic stretching into a third year.

“The administration is focused on things that are important but not particularly salient to voters and sometimes as president you have to do that,” said Matt Bennett, a co-founder of Third Way, a moderate Democratic think tank. “Now, we need to begin to move back to talking about the things that people do care about.