The administration’s decision appeared to end a yearlong battle over whether the Commerce Department broke the law when it decided in March 2018 to tack a citizenship question onto the census, long after other aspects of the questionnaire had been finalized.
The department, which oversees the Census Bureau, had argued that the Justice Department needed a more accurate count of citizens to enforce the 1965 Voting Rights Act, but three lower courts ruled that that was an obvious pretext for some other unstated goal.
The department’s explanation was further undermined last month after plaintiffs uncovered computer files from a deceased Republican political strategist, Thomas B. Hofeller, who had first urged the incoming Trump administration in 2016 to consider adding the question to the next census.
The files included a study in which Mr. Hofeller concluded that a citizenship question was central to a strategy to increase Republican political power by excluding noncitizens and persons under voting age from the census figures used for drawing new political boundaries in 2021.
The disclosure led to the reopening of one of the lawsuits opposing the question, and plaintiffs were scheduled to begin new efforts this month to prove that the question was an effort to discriminate against Hispanics for political gain.
On Tuesday, one of the plaintiffs in that suit, the Mexican American Legal Defense and Educational Fund, indicated that it was unwilling to end the lawsuit without further assurances from the administration that the issue of the citizenship question had been fully resolved.
Thomas A. Saenz, the organization’s president and general counsel, said his group wanted to make sure there wasn’t any misinformation spread about there still being a citizenship question.
“No matter what happens, there’s still a lingering hardship from how long the administration had this hanging out there, and the publicity it got,” he said.