Many Democratic lawmakers continued to express deep frustration at Senator Chuck Schumer on Sunday for having broken with most of his party to allow a Republican spending bill to pass, as the Democratic base increasingly demands stauncher resistance to President Trump’s far-reaching agenda.

Mr. Schumer, a New York Democrat and the Senate minority leader, joined nine other Democrats in allowing the bill to come to a vote, which averted a government shutdown. It was an abrupt reversal from Wednesday, when he said he would oppose the bill.

Explaining his sudden shift in position, Mr. Schumer argued that a shutdown would empower Mr. Trump and Elon Musk’s Department of Government Efficiency. “A shutdown would shut down all government agencies, and it would solely be up to Trump and DOGE and Musk what to open again, because they could determine what was essential,” he told The New York Times in an interview. “So their goal of decimating the whole federal government, of cutting agency after agency after agency, would occur under a shutdown.”

But to critics within his own party, he had squandered the leverage provided by the standoff to negotiate a bipartisan spending bill that would reclaim some of Congress’s power.

“He is absolutely wrong,” Representative Jasmine Crockett, Democrat of Texas, told CNN on Sunday. “The idea that Chuck Schumer is the only one that’s got a brain in the room and the only one that can think through all of the pros and cons is absolutely ridiculous.”

The stream of criticism that Mr. Schumer has faced since his vote comes as the Democratic Party is divided on how best to oppose Mr. Trump’s agenda while facing dismal polling numbers. An NBC poll released on Sunday showed that just 27 percent of voters had positive views of the party, while a majority of its base expressed disappointment at the Democrats’ fractured response.

Ms. Crockett has called on her Senate colleagues to consider ousting Mr. Schumer as minority leader, suggesting that “a younger, fresher leadership” is what “many Americans may be looking for.”

Representative James E. Clyburn, Democrat of South Carolina, told MSNBC that the House minority leader, Representative Hakeem Jeffries of New York, “got blindsided” by Mr. Schumer. House Democrats — all but one opposed the bill — had voted against giving Mr. Trump “a blank check,” Mr. Clyburn said. On Friday, Mr. Jeffries dodged repeated questions on whether he still supported Mr. Schumer as the leader of Senate Democrats.

Another House Democrat, Representative Debbie Dingell of Michigan, was a little more understanding, saying that Mr. Schumer had “sent out mixed signals.” But she stressed that even the American Federation of Government Employees, the largest labor union representing federal workers, whose members would be furloughed during a government shutdown, opposed the stopgap bill.

“People are scared, and they want us to do something,” Ms. Dingell said on CBS. “They want to see Democrats fighting back.”

Senator Chris Murphy, Democrat of Connecticut, did not denounce Mr. Schumer but pleaded for a change in tactics and for a more steadfast resistance against the Trump administration.

“The way the president is acting using law enforcement to target dissidents, harassing TV stations and radio stations that criticize him, endorsing political violence, puts our democracy at immediate risk,” Mr. Murphy said on NBC. Over the past few weeks, Mr. Trump has revoked security clearances of lawyers who argued against him, dismantled congressionally funded news agencies and pardoned those convicted of attacking the Capitol on Jan. 6, 2021.

Mr. Murphy added, “If you are a Democrat in the Senate or in the House you have to start acting with urgency.”

Prominent House Democrats, including Representative Nancy Pelosi, had pressed their Senate colleagues to block the bill. But more than a handful of Democratic senators joined Mr. Schumer in helping Republicans bring the bill to a vote: Dick Durbin of Illinois, Brian Schatz of Hawaii, Catherine Cortez Masto of Nevada, John Fetterman of Pennsylvania, Kirsten Gillibrand of New York and Maggie Hassan of New Hampshire, as well as two who have announced plans to retire, Gary Peters of Michigan and Jeanne Shaheen of New Hampshire. Senator Angus King, the Maine independent who caucuses with Democrats, also voted yes.

Some Democrats, including Representatives Jake Auchincloss of Massachusetts and Haley Stevens of Michigan, refrained from openly criticizing Mr. Schumer’s shift. They said Democratic infighting after the bill’s passage would only emphasize the divisions within the party. They warned that it would also draw voters’ attention away from Trump trade policies that have dampened the stock market and imbued uncertainty into the broader economy — developments that Democrats said could play to their advantage.

Ashley Etienne, a former communications director for Vice President Kamala Harris, told CNN that Democrats should not save Mr. Trump and Republicans from themselves. “Get out of the way,” she said. “Donald Trump said he was better for the economy. Let him prove it.”

This week, government workers near the White House, on two blocks lined with luxury hotels and union headquarters, used a jackhammer and a pickax to tear up a mural that read “Black Lives Matter,” painted on the road during the long hot summer of 2020.

The symbolism was potent.

The erasure of the bold yellow letters of Black Lives Matter Plaza, installed on 16th Street after the murder of George Floyd by a Minneapolis police officer, was a concession from Washington’s mayor, Muriel Bowser, who faced threats from congressional Republicans to cut off federal funds to the capital city if the words were not removed. But to Black Americans grappling with a fierce resurgence of forces that they believe are beating back the causes of social justice and civil rights, it felt like much more.

That plaza was “spiritual,” said Selwyn Jones, an uncle of Mr. Floyd. “But them taking the time to destroy it, that’s making a statement, man. That’s making a statement, like we don’t care.”

Even those who did not put much faith in the mural to begin with were taken aback.

“Bowser caving immediately to the faintest hint of pressure on the name of the plaza is somehow even more cynical than the move to name it Black Lives Matter Plaza in the first place,” said Olúfẹ́mi O. Táíwò, a Black associate professor of philosophy at Georgetown.

“We saw the largest protest movement in our nation’s history, a unique and powerful moment where it seemed anything was possible, and you had the numbers to do anything,” lamented Samuel Sinyangwe, executive director of the nonprofit Mapping Police Violence, without exaggeration.

The millions of dollars that flowed to groups with “Black Lives Matter” in their titles have slowed to a trickle, forcing some to retrench, others to close shop. The Black Lives Matter Foundation Inc., for instance, raised a staggering $79.6 million in fiscal year 2021. The next year, that figure was down to almost $8.5 million. By 2023, it was about $4.7 million, with expenses of $10.8 million, according to records tracked by the nonprofit journalism organization ProPublica.

As it recedes, Mr. Trump has sought to bury it. In two short months, his administration has moved to end diversity, equity and inclusion as goals of the federal government and pressured private industry to do the same. It shut down the National Law Enforcement Accountability Database, which tracked the misconduct records of federal law enforcement officers.

Words with even a hint of racial, ethnic or gender sensitivities are being struck from federal websites and documents. Just this week, the Environmental Protection Agency moved to eliminate offices responsible for addressing the disproportionately high levels of pollution facing poor communities, often with predominantly minority residents.

The billionaire White House adviser Elon Musk has even said pardoning George Floyd’s killer was “something to think about.”

Beyond Washington, journalists and academics who vaulted to stardom a half decade ago on their reinterpretations of history, their views on racism and their valorizing of the African American experience find themselves sometimes marginalized, and often under attack.

“I feel we are going backwards,” Mr. Jones said.

Given the swift change of circumstances, some in the Black Lives Matter movement say they must answer an existential question: How do they pursue racial justice amid so fierce a backlash?

“Folks got sold a bag of goods under this idea of racism and xenophobia,” said Addys Castillo, a social justice organizer and law student in Connecticut.

But, she said, the administration’s policies will hurt all those who aren’t wealthy, “so if there was ever a time to have a multiracial, cross cultural movement, this would be the time.”

James Forman Jr., a former public defender, an author and a fierce critic of the criminal justice system and its effects on people of color, said persuading all Americans that a system that has harmed Black Americans has harmed them too is difficult — but crucial.

“It’s always been hard to be able to get people to see two things at the same time: the ways in which these institutions disproportionately harm Black people, and the way that these institutions harm all people,” he said.

Ms. Bowser, who is Black, told laid-off federal workers earlier this month that the mural was a significant part of the city’s history, but circumstances have changed. “Now our focus is on making sure our residents and our economy survive,” she said.

Observers say the racial justice movement that crescendoed after Mr. Floyd, an unarmed Black man, was murdered by a Minneapolis police officer in May 2020 had some successes, at least in raising public awareness about structural racism and police violence.

Protesters and Black activists pressed people to evolve from support for civil rights as “mere etiquette” to “an understanding that actual institutions, political institutions, criminal justice institutions had to be challenged to work differently,” Mr. Táíwò said.

But the movement must mature, said Representative Wesley Bell, a Missouri Democrat who rose to prominence after the police shooting of a Black teenager, Michael Brown, in the St. Louis suburb of Ferguson. Mr. Bell, who is Black, defeated one of the most demonstrative Black progressives in the House, Cori Bush, in a heated primary last year, promising voters to bring Greater St. Louis a more sober, effective leadership.

“Some folks think it’s just about getting out and protesting,” said Mr. Bell, who advocates moving the social justice cause from the streets to the corridors of power. “The best protesters do not make the best politicians, and the best politicians don’t make the best protesters.”

Black Lives Matter began as an online hashtag after the 2013 acquittal of George Zimmerman in the shooting death of Trayvon Martin, an unarmed Black teenager. But the phrase coalesced into a movement after the killing of Michael Brown the following year.

From the beginning the phrase drew attacks.

“When you say ‘Black lives matter,’ that’s inherently racist,” the former New York City mayor Rudolph W. Giuliani said in 2016. “Black lives matter. White lives matter. Asian lives matter. Hispanic lives matter.”

Four years later, as he campaigned unsuccessfully for re-election, Mr. Trump accused supporters of Black Lives Matter of “spreading violence in our cities” and “hurting the Black community.”

But in the summer of 2020, millions of Americans took to the streets from all walks of life. Conservative voices, like the president of the Heritage Foundation and Mr. Trump’s former ambassador to the United Nations, Nikki Haley, lamented Mr. Floyd’s murder.

Some of the protests turned violent. A Minneapolis police station was burned to the ground. The calls for incremental police reform became drowned by the rallying cry, “defund the police.”

And that gave Mr. Trump his most potent line of attack against the movement. He reframed a cause that hoped to protect Black lives as a lawless assault on police officers. In his telling, the leaders of the movement were avatars for every left-wing cause in his sights.

Because of the Black Lives Matter movement’s decentralized structure, many groups were lumped together and faced intense scrutiny, often with negative consequences for the movement as a whole.

“Any strategic or tactical misstep for the movement is going to produce more severe and swift negative consequences,” Mr. Forman said.

The Black Lives Matter Global Network Foundation, for instance, faced criticism that it misused funds, including the purchase of a $6 million California home.

“I’m not particularly happy with the organization Black Lives Matter, because of their shenanigans,” said Mr. Jones.

“Black Lives Matter, they are not a perfect organization,” said Angela Harrison, an aunt of Mr. Floyd. “They probably made mistakes. Everyone makes mistakes. But their intention was for the good.”

But mistakes added up. The movement to examine historical ways racism has shaped current disparities in areas such as housing and wealth creation gave way to the opposite. Conservative activists successfully pushed state governments to ban teachings that they said made people feel inherently responsible for actions committed in the past.

Corporations that once made a show of racial, ethnic and gender sensitivities have begun rolling back their diversity initiatives, seemingly more afraid of the conservative activists fighting them than the social justice activists who had supported them, said Damon Hewitt, president and executive director of the Lawyers’ Committee for Civil Rights Under Law.

That, he said, “could certainly suggest that maybe the belief isn’t strongly held, but also more of a sense of resignation.”

Mr. Sinyangwe is taking a long view and sees parallels and patterns with many historical movements for social justice.

“This movement has followed the trajectory that freedom struggles in the United States have always tended to follow,” he said.

A marginalized community pushes back against injustice. Some of its demands are met, but others don’t materialize. So they push for more transformative changes only to be met with backlash. “And that’s sort of how America does business,” he said. “That’s not the fault of anyone’s slogan.”

In June 2020, after Mr. Trump marshaled federal law enforcement and the military to violently confront protesters outside the White House, Ms. Bowser announced that she was renaming a street just off the protest site “Black Lives Matter Plaza,” complete with 48-foot letters on the pavement.

The mayor’s decision to remove the letters with Mr. Trump’s return to power has been met with ambivalence. Some agree that Ms. Bowser has more pressing concerns, such as budget cuts and the slashing of the federal work force in her city.

“The painting ain’t saving any of us,” said Ms. Castillo.

Others are gearing up for a fight that will outlive any one presidency.

“I don’t believe we’ll ever be in a place where there won’t be a fight,” Mr. Bell said. “But I will say this — I don’t think that President Trump can stop progress either.”