A group spearheaded by former U.S. attorney general Eric H. Holder Jr. is suing the Trump administration in an attempt to block its plans to add a last-minute citizenship question to the 2020 Census.

The federal lawsuit, to be filed Wednesday on behalf of seven residents of Maryland and Arizona, contends that the question is at odds with the constitutional requirement that the census count every person residing in the United States, including noncitizens.

Commerce Secretary Wilbur Ross announced the addition of the question last month, triggering an outcry from immigrant advocacy groups and Democratic lawmakers, who stand to lose political power if undocumented immigrants and their families don't respond to the survey.

“Coming amidst what the Bureau itself has identified as a widespread climate of fear among citizen and noncitizen immigrants, the belated addition of a citizenship question will significantly depress response rates in certain communities, thereby undermining the completeness and the accuracy of the 2020 census,” the lawsuit states. Holder’s group plans to file it in the U.S. District Court for the District of Maryland.

The lawsuit makes a similar argument to other actions brought in recent weeks by an array of states and localities, but it is the first being filed on behalf of individual residents who the suit says will be adversely affected.

“This lawsuit is a direct challenge from affected individuals,” said Holder, who chairs the National Democratic Redistricting Committee, which is seeking to help Democrats as congressional lines are redrawn, a process informed by census results.

The lawsuit is being coordinated by the National Redistricting Foundation, a nonprofit organization affiliated with the committee Holder chairs.

In an interview, Holder, who served as attorney general under President Barack Obama, said residents of Maryland and Arizona were selected to underscore that the citizenship question has negative consequences on those living in states with different political leanings.

“Blue states as well as red states are impacted by this,” he said.

He said residents from other states might be added to the lawsuit later.

Officials in Arizona have declined to join other lawsuits challenging the Trump administration. Maryland is among the plaintiffs in a separate suit that includes 17 states and the District.

Census tallies are used to determine the distribution of representation and resources, including the number of seats in the House, the number of electoral college votes and the apportionment of hundreds of billions of federal dollars each year.

Ross has argued that data from a citizenship question could help identify potential voting-rights violations by providing more accurate information than currently available about the proportion of a congressional district’s population that is eligible to vote by virtue of holding citizenship. Information about citizenship currently comes from a survey that samples a small percentage of the population.

Holder was dismissive of that argument, saying the current process was sufficient for enforcing the Voting Rights Act.

Michael Scherer and Tara Bahrampour contributed to this report.