Immigration activists are slamming the Department of Justice over a proposed addition to the United States census.

The proposal would add a question of one's citizenship status to the next census survey, which is in 2020.

Activists say that question can deter countless people from answering the survey, arguing that noncitizens may fear retribution for answering negatively and could skip the census entirely. If that happens, they say immigration clusters like those in New York would suffer. The census would count fewer people and, in turn, lead to fewer resources.

The census is overseen by the Department of Commerce. Because of that, more than two dozen advocacy organizations have penned a letter to commerce Secretary Wilbur Ross to reject the DOJ's proposal.

"Adding a citizenship question -- especially at such a late date in the 2020 census planning process -- would significantly depress participation, causing a population undercount that would disproportionately harm states and cities with large immigrant communities," the letter reads in part.

The DOJ says the data is critical to protect all American citizens' voting rights.

The U.S. Census Bureau must submit a final list of the 2020 census questions to Congress by March 31.