Reacting to a spate of news reports of new evidence suggesting that Trump administration officials misled Congress and courts on their motives for adding a citizenship question to the 2020 Census, the Justice Department has come out swinging.

The story broke on Thursday when attorneys for the American Civil Liberties Union—who had previously won in district court in their challenge to the Commerce Department’s stated rationale for adding the question—submitted an amended court filing to Judge Jesse Furman of the Southern District of New York.

The development also comes as the Government Accountability Office released a report on ongoing risks in preparations for the 2020 census, with commentary on the citizenship question dilemma.

The new information delivered by the ACLU team came from the daughter of the deceased Republican expert on the politics of legislative district map drawing, Thomas Hofeller. The documents she shared appear to show that her father had conducted a 2015 study indicating that adding the question would reduce the political power of presumably Democratic-leaning Latinos. And Hofeller played an active role in pushing the Commerce and Justice Departments to make the change, the documents contained on external hard drives and thumb drives showed.

The addition of the controversial question was then justified on the premise that it would facilitate collection of census district data to help with enforcement of the Voting Rights Act, the rationale maintained by Commerce Secretary Wilbur Ross; John Gore, the principal deputy assistant attorney general for the Civil Rights Division at the Justice Department; and Trump transition team census specialist Mark Neuman.

Census data scientists have long argued that such a question on the sensitive topic of whether a respondent is a legal immigrant would hamper participation among Latinos and harm the survey’s accuracy. And Democrats in Congress have sought to expose what they see as a Trump administration bid to influence the coming 2021 congressional district maps by reducing the Latino count and favoring Republicans.

The question of whether Commerce can require the Census Bureau to add the question was heard by the Supreme Court in April, and a ruling is expected in June.

In a Friday statement to Government Executive, a Justice spokesperson repeated an earlier position dismissing the plaintiffs’ claim that the motives for adding the question were political. “These eleventh-hour allegations by the plaintiffs, including an accusation of dishonesty against a senior Department of Justice official, are false,” the statement said. “Before today, Mr. Gore had never heard of the unpublished study apparently obtained from the personal effects of a deceased political consultant. That study played no role in the department’s December 2017 request to reinstate a citizenship question to the 2020 decennial census. These unfounded allegations are an unfortunate last-ditch effort to derail the Supreme Court’s consideration of this case. The department looks forward to responding in greater detail to these baseless accusations in its filing on Monday.”

In the new filing in the New York court, the ACLU team working with attorneys with Arnold & Porter Kaye Scholer described the 2015 study by political adviser Hofeller as concluding that a citizenship question “would be advantageous to Republicans and non-Hispanic whites.” They continued: “Based on this new evidence, it appears that both Neuman and Gore falsely testified about the genesis of the DOJ’s request to Commerce in ways that obscured the pretextual character of the request. …The new evidence thus not only contradicts testimony in this case, but shows that those who constructed the [Voting Rights Act] rationale knew that adding a citizenship question would not benefit Latino voters, but rather would significantly reduce their political power.”

The Census Bureau, meanwhile, has forged ahead with planning for the big count with forms designed both to include the citizenship question and not including it, reporting that the Supreme Court has been made aware of the need for a quick decision.

But the Friday GAO report said, “With less than one year until Census Day, many risks remain. For example, the bureau has had challenges developing critical information technology systems, and new innovations—such as the ability to respond via the Internet—have raised questions about potential security and fraud risks.”

Back in December, auditors had identified 360 active risks, of which 242 required a formal mitigation plan—232 of which were completed. ”Bureau officials said that risk owners are aware of these responsibilities but do not always fulfill them given competing demands. Bureau officials also said that they are managing risks to the census, even if not always reflected in their mitigation and contingency plans.”

The uncertainty of the citizenship question is one of the “most likely foreseeable late operational design changes” that risk managers are planning around. “The mitigation plan for this activity included all key activities,” GAO acknowledged. “However, the bureau’s contingency plan for this risk included no activities specific to these scenarios that the bureau could carry out to lessen their adverse impact on the enumeration, should they occur.”

Census officials told GAO that the “bureau’s contingency plan for this risk is a rapid response approach, which does not require the bureau to specify contingency activities in the event the risk is realized.” Even so, the officials have planning contingencies in case of a late design change for the questionnaire and other tools. “For example, they said they would use their change control process to assess impacts and facilitate decision-making…. including flexibility to make changes to the automated instruments for Internet self-response, census questionnaire assistance, and nonresponse follow-up.”

GAO warned, however, that the bureau had not documented these activities in its contingency plan. “Without including all key activities in the contingency plan for this risk, the bureau may not be able to respond as quickly to lessen any adverse impacts should a late design change occur,” the watchdog said.