Midway through the 2022 primary season, many Democratic lawmakers and party officials are venting their frustrations with President Biden’s struggle to advance the bulk of his agenda, doubting his ability to rescue the party from a predicted midterm trouncing and increasingly viewing him as an anchor that should be cut loose in 2024.

As the challenges facing the nation mount and fatigued base voters show low enthusiasm, Democrats in union meetings, the back rooms of Capitol Hill and party gatherings from coast to coast are quietly worrying about Mr. Biden’s leadership, his age and his capability to take the fight to former President Donald J. Trump a second time.

Interviews with nearly 50 Democratic officials, from county leaders to members of Congress, as well as with disappointed voters who backed Mr. Biden in 2020, reveal a party alarmed about Republicans’ rising strength and extraordinarily pessimistic about an immediate path forward.

“To say our country was on the right track would flagrantly depart from reality,” said Steve Simeonidis, a Democratic National Committee member from Miami. Mr. Biden, he said, “should announce his intent not to seek re-election in ’24 right after the midterms.”

Democrats’ concerns come as the opening hearing of the House committee investigating the Jan. 6 attack on the Capitol made clear the stakes of a 2024 presidential election in which Mr. Trump, whose lies fueled a riot that disrupted the peaceful transfer of power, may well seek to return to the White House.

For Mr. Biden and his party, the hearings’ vivid reminder of the Trump-inspired mob violence represents perhaps the last, best chance before the midterms to break through with persuadable swing voters who have been more focused on inflation and gas prices. If the party cannot, it may miss its final opportunity to hold Mr. Trump accountable as Mr. Biden faces a tumultuous two years of a Republican-led House obstructing and investigating him.

Most top elected Democrats were reluctant to speak on the record about Mr. Biden’s future, and no one interviewed expressed any ill will toward Mr. Biden, to whom they are universally grateful for ousting Mr. Trump from office.

But the repeated failures of his administration to pass big-ticket legislation on signature Democratic issues, as well as his halting efforts to use the bully pulpit of the White House to move public opinion, have left the president with sagging approval ratings and a party that, as much as anything, seems to feel sorry for him.

Worries about age, and a successor

To nearly all the Democrats interviewed, the president’s age — 79 now, 82 by the time the winner of the 2024 election is inaugurated — is a deep concern about his political viability. They have watched as a commander in chief who built a reputation for gaffes has repeatedly rattled global diplomacy with unexpected remarks that were later walked back by his White House staff, and as he has sat for fewer interviews than any of his recent predecessors.

“The presidency is a monstrously taxing job and the stark reality is the president would be closer to 90 than 80 at the end of a second term, and that would be a major issue,” said David Axelrod, the chief strategist for Barack Obama’s two winning presidential campaigns.

“Biden doesn’t get the credit he deserves for steering the country through the worst of the pandemic, passing historic legislation, pulling the NATO alliance together against Russian aggression and restoring decency and decorum to the White House,” Mr. Axelrod added. “And part of the reason he doesn’t is performative. He looks his age and isn’t as agile in front of a camera as he once was, and this has fed a narrative about competence that isn’t rooted in reality.”

Mr. Biden has repeatedly said that he expects to run again in 2024. But if he does not, there is little consensus about who would lead the party.

These Democrats mentioned a host of other figures who lost to Mr. Biden in the 2020 primary: Senators Amy Klobuchar of Minnesota, Bernie Sanders of Vermont, Elizabeth Warren of Massachusetts and Cory Booker of New Jersey; Transportation Secretary Pete Buttigieg; and Beto O’Rourke, the former congressman who is now running for Texas governor, among others.

Mr. Biden’s supporters insist he has the country on the right track, despite the obstacles.

“Only one person steered a transition past Trump’s lies and court challenges and insurrection to take office on Jan. 20: Joe Biden,” said Anita Dunn, a senior adviser to the president, citing strong jobs numbers and efforts to combat the pandemic.

Other Biden allies dismissed suggestions that any other Democrat would do better than him in 2024.

“This the same hand-wringing that we heard about Barack Obama in 2010 and 2011,” said Ben LaBolt, who worked on Mr. Obama’s campaigns.

Cristóbal Alex, who was a senior adviser for the Biden campaign and was the deputy cabinet secretary in the White House until last month, said Mr. Biden was the only Democrat who could win a national election.

Mr. Alex said it was the responsibility of congressional Democrats to highlight Mr. Biden’s successes and pass legislation he, and most of them, campaigned on.

“I am worried that leaders in the party aren’t more aggressively touting the success of the administration,” he said. “The narrative needs to shift, and that can only happen with a powerful echo chamber combined with action in Congress on remaining priorities. The American people feel unsettled.”

Nikki Fried, the Florida agriculture commissioner who is running for governor, said she would welcome Mr. Biden to campaign with her in Florida, but stopped short of endorsing him for a second term. “There is a lot of time between now and 2024,” she said.

Still, public polling shows that Mr. Biden is at a low point in his popularity among Democratic voters. A survey last month from The Associated Press found Mr. Biden’s approval among his fellow party members at 73 percent — the lowest point in his presidency, and nine points lower than at any point in 2021. There is little recent public polling asking if Democrats want Mr. Biden to seek a second term, but in January just 48 percent of Democrats wanted him to run again, according to The A.P.’s polling.

‘We’re lacking in the excitement’

Elected Democrats are cautious about openly discussing Mr. Biden’s future.

“I’m not allowed to have feelings right now,” said Jasmine Crockett, a Texas state representative who last month won a primary runoff for a heavily Democratic House seat based in Dallas. “When you’re an incoming freshman, you just don’t get to.”

Still, Ms. Crockett lamented a stark enthusiasm gap between Republicans, who in Texas have passed legislation to restrict voting rights and abortion rights while expanding gun rights, and Democrats, who have not used their narrow control of the federal government to advance a progressive agenda.

“Democrats are like, ‘What the hell is going on?’” Ms. Crockett said. “Our country is completely falling apart. And so I think we’re lacking in the excitement.”

Many Democratic leaders and voters want Mr. Biden to fight harder against Republicans, while others want him to seek more compromise. Many of them are eyeing 2024 hoping for some sort of idealized nominee — somebody who isn’t Mr. Biden or Ms. Harris.

Hurting Mr. Biden the most, said Faiz Shakir, who was campaign manager for Mr. Sanders in 2020, is a perception of weakness.

Mr. Shakir circulated a memo in April stating that Mr. Sanders “has not ruled out” running in 2024 if Mr. Biden does not. In an interview, Mr. Shakir said he believed that Mr. Biden could beat Mr. Trump a second time — but that if Republicans nominate a newer face, like Gov. Ron DeSantis of Florida, Mr. Biden may not be the best choice.

“If it’s DeSantis or somebody, I think that would be a different kind of a challenge,” Mr. Shakir said.

Howard Dean, the 73-year-old former Vermont governor and Democratic National Committee chairman who ran for president in 2004, has long called for a younger generation of leaders in their 30s and 40s to rise in the party. He said he had voted for Pete Buttigieg, 40, in the 2020 primary after trying to talk Senator Chris Murphy, 48, of Connecticut into running.

“The generation after me is just a complete trash heap,” Mr. Dean said.

Mr. Biden and other older Democratic leaders in Washington, Mr. Dean said, have spent far too much time articulating goals that they have not reached.

“We need to have specific examples of how we’re dealing with things; it can’t just be pie-in-the-sky and kumbaya,” he said.

Many Democratic voters feel similarly. Lamenting “a great national loss of hope,” Alex Wyshyvanuk, 33, a data analyst from Annapolis, Md., said he wasn’t sold on another Biden presidential campaign in 2024.

“I need an equivalent of Ron DeSantis, a Democrat, but not a 70- or 80-year-old — a younger person,” he said. “Someone who knows what worked for you in 1980 is not going to work for you in 2022 or 2024.”

Regret and anxiety

And then there are the questions about Mr. Biden’s inability to persuade centrist Democratic senators to back his agenda. With the prospect looming of a Republican majority in at least one chamber of Congress next year, Democrats who have been in a similar position of holding fleeting control of government are nervous that past mistakes will be repeated.

Elizabeth Guzmán, a member of the Virginia House of Delegates, said Democrats in her caucus regret not passing a sweeping abortion rights law last year before they lost control of the state House and governor’s mansion to Republicans.

“We wanted to codify Roe vs. Wade, and look what happened,” she said.

Judy Vidal, 58, a retail worker from Cape Coral, Fla., echoed that sentiment.

“I just wish that since we have the majority now they would have behaved the way Republicans did and push things through,” she said.

The anxiety about Mr. Biden extends to the core of his political base. Adrianne Shropshire, the executive director of BlackPAC, an African American political organizing group, said her chief concern was that Black voters, having watched Mr. Biden and Democrats fail to deliver on core promises, don’t come back to vote in November.

“Does this frustration and the malaise and the worry and the fear, does that translate into an ongoing enthusiasm gap, and does that cause people to feel like their participation doesn’t make significant change?” she said. “That’s the real question.”

Even some of the earliest supporters of Mr. Biden’s 2020 campaign are now questioning whether he can lead the party through another daunting election cycle against Mr. Trump.

Ann Hart, a Democratic Party co-chairwoman in Iowa’s Allamakee County, endorsed Mr. Biden ahead of the state’s 2020 caucuses and introduced him at a campaign stop in a neighboring county. Ms. Hart, a retired school principal, said she could not imagine how Mr. Biden manages the presidency at 79 years old.

“I get asked to run for things — are you kidding? I’m 64,” she said. “We need youth. So I kind of admire him wanting to take this on and I hope he’ll pass the torch.”

Shelia Huggins, a lawyer from Durham, N.C., who is a member of the Democratic National Committee, put it more bluntly.

“Democrats need fresh, bold leadership for the 2024 presidential race,” she said. “That can’t be Biden.”