(CNN) The Department of Justice on Monday night forcefully disputed an account by the American Civil Liberties Union, Common Cause and others that the decision to add a citizenship question to the census was politically motivated.

A Justice Department spokesperson says the allegations that a 2015 study by a Republican redistricting expert played a major role in the request to add a citizenship question to the census are meritless.

In a letter last week, the ACLU, Common Cause and others said they had found "new evidence" that the government's true motivation in adding the question was to improve the chances of Republicans.

They pointed to a recently disclosed 2015 study written by Dr. Thomas Hofeller, a Republican redistricting expert, who wrote that using "citizen voting age" population as the redistricting population base would be "advantageous to Republicans and Non-Hispanic Whites."

The challengers say the new information shows Hofeller played a more significant role in the decision to add the citizenship question than has been disclosed and that his study reveals the true motive behind the administration's decision to add the question. Meanwhile, challengers in a separate case in Maryland, citing the Hofeller evidence, asked a federal judge on Tuesday to reopen their case to reconsider whether the Trump administration sought to intentionally discriminate against Latinos and immigrants.

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