On Thursday afternoon at the Villas at Langley housing complex in Hyattsville, where women strolled with babies swaddled in the colorful fabrics of their native Guatemala, Julia Aviles-Zavala knocked on an apartment door.

Music from inside was audible, but no one answered. She knocked again, and then again. Finally, the door opened slightly and a man peered out.

“Hello. My name is Julia and I’m here on the part of CASA de Maryland, to talk with you about the census,” she said in Spanish. “Have you heard about the census?”

“A little,” the man said warily.

Aviles-Zavala launched into her practiced pitch about the decennial survey — how it is a government-mandated count of every person living in the United States, how it is important for determining federal funding and political representation, how it is confidential and private and safe, even for immigrants.

That last part is key. The run-up to the 2020 Census — April 1 is officially Census Day — has been fraught with political and legal turmoil after the Trump administration tried to add a citizenship question to the survey. The effort was ultimately blocked by the Supreme Court.

Opponents of the question accused the government of trying to scare immigrant communities from responding, thus reducing their political power and funding streams. And even though the question won’t be on the form, advocates say the publicity around it, along with what they see as the administration’s anti-immigrant policies and rhetoric, magnified fears about sharing personal information and set back efforts to get people in immigrant communities — already a hard-to-count group — to fill it out.

CASA, an immigrant advocacy group, last week launched its I Count/Yo Cuento campaign for Maryland, with television, radio and digital ads and a cartoon character named Lucas, a 13-year-old Latino boy who will appear in them to encourage participation.

The organization, which serves Maryland, Virginia, and Pennsylvania, was one of several civil rights groups and jurisdictions that sued the government over the citizenship question. Its members began knocking on doors in November, but the campaign will expand in the coming months.

“The Trump administration has a strategy to make sure that our community isn’t going to be counted,” Gustavo Torres, CASA’s executive director, said during the launch at the group’s Hyattsville headquarters. “We’re not going to let the Trump administration do what they wanted to do.”

The stakes are high. The NAACP alleges that Prince George’s County had the largest net undercount of any county in Maryland in the previous census, and one of the nation’s largest undercounts for counties of 100,000 or more residents. Lawyers for the organization think that undercount cost the county about $363 million in federal funds.

Prince George’s is a majority minority county, with 64 percent of its residents identifying as African American in the last census and an additional 19 percent identifying as Hispanic. The census tends to overcount groups such as whites and homeowners, and undercount minorities, children and people with lower incomes.

The 2010 Census undercounted 2.1 percent of the black population and 1.5 percent of the Hispanic population; it overcounted non-Hispanic whites by 0.8 percent, according to the Census Bureau.

In surveys conducted since the citizenship question was blocked, about half of Latinos still thought the question would appear on the form, said Lizette Escobedo, director of the national census program for NALEO, a Latino advocacy group. “That is a massive concern for us, because a lot of the damage has been done.”

Even without the question, many fear that filling out the form could lead to scrutiny by police or U.S. Immigration and Customs Enforcement agents. Advocacy efforts have focused on educating people about what will and won’t be on the form, how the data will be used, what an enumerator will look like if one comes to the door and how people can avoid an enumerator’s visit by responding to the bureau’s initial request to fill out the form.

By law, the bureau cannot disclose or share individual respondents’ information with anyone, including other government agencies; the data that is released is aggregated and does not allow for personal identification. Consequences for an enumerator who shares census data include a fine of up to $250,000 or up to five years’ imprisonment.

The bureau has launched its own gigantic ad campaign to encourage participation. But its ads do not specifically indicate that the citizenship question won’t appear on the form, in part, the advertising team said, because the campaign was developed before the outcome of the litigation.

That leaves it to advocates to fill in the gaps at a time when immigrant communities are more skittish than during the 2010 Census.

“We’re having to deal with this whole other landscape,” Escobedo said. “The distrust of government has always been there in our community, but now it’s really been amplified. It’s up to the community groups to recognize that the fears in our community are well-placed, and how do we work from there?”

At a time when the highest levels of government are being investigated for allegedly breaking the rules, even some advocates wonder how safe the data is.

“When I trained my internal field staff, those were some of the concerns — ‘We’re telling people that the data is safe, secure and confidential, but is it, though?’ ” Escobedo said.

CASA members remind constituents that many of them already share personal information with the government in other ways. “Do you file your taxes? When you get a job, do you fill out a W-2?” said Elizabeth Alex, chief of organizing for CASA. “When we put it in that type of a light, people understand.”

Advocates explain that the Census Bureau is staffed by career professionals and data scientists, many of whom remain in their positions regardless of the administration in the White House.

They also tell people there is extensive legal and political machinery poised to spot and combat any attempts to circumvent census laws.

“You say it’s confidential, but these are weird times,” Alex said. “What if somebody tries to make it not confidential? We can say honestly we will fight back . . . and you can see that we did that because we won,” in the litigation over the citizenship question.

Repetition of the messages over a long period is key, said Vanita Gupta, president and chief executive of the Leadership Conference Education Fund, which runs Census Counts, a campaign that organizes national, state and local organizations around the census. Over the past four decades that it has done so, this is the largest coordinated effort, she said.

“It’s started already and it needs to be put on steroids over the next couple of months, so that we can combat the fear and make sure that everyone is counted,” she said. “The good news is the specter of the citizenship question and that year-long fight has really energized and engaged advocates and local elected officials . . . to start the outreach and engagement much, much earlier.”

On Thursday, about half the doors Aviles-Zavala knocked on went unanswered. Among the people who opened the door, nobody wanted to share their name with a news reporter. But after hearing her pitch for how being counted could improve services such as health care, roads and schools, they agreed to Aviles-Zavala’s request that they sign a pledge saying they would fill out the census form.

“A lot of people are worried,” she told them. “But I’m here to tell you that it’s safe.”