The Department of Justice (DOJ) is trying to convince the Census Bureau to add a question about citizenship status to 2020 census forms, according to a DOJ letter released Friday.

The December 12 letter from DOJ lawyer Arthur Gary to Census Bureau official Dr. Ron Jarmin said the bureau should include the citizenship question as a way to enforce the Voting Rights Act.

“To fully enforce those requirements, the Department needs a reliable calculation of the citizen voting-age population in localities where voting rights violations are alleged or suspected,” the letter said.

The Census Bureau acknowledged the letter’s existence, telling ProPublica that the letter’s “request will go through the well-established process that any potential question would go through.”

The letter comes as several reports during the past few months have hinted that the Trump administration would include an immigration status question in the 2020 census.

Critics say that including an immigration-related question could cause a “chilling effect” on the Census response rate, while supporters say it would help ensure the integrity of future elections.