(CNN) The Census Bureau's own researchers are warning what critics of the controversial citizenship question have long contended, that it will lead to lower response rates on the 2020 census, CNN has learned.
"Hispanics believe the census would be used to find undocumented people," they concluded and presented to the bureau's advisory committee on Thursday.
Asking whether those in households filling out census forms are US citizens "may be a major barrier" to gaining census responses, they wrote. Respondents' concerns included that the purpose of the question "is to find undocumented immigrants" and "political discourse is targeting their ethnic group -- residents and citizens may also feel endangered."
The findings were part of a survey -- comprising 17,500 responses as well as 42 focus groups -- that the Census Bureau conducted from February to April to guide its communications and outreach plans for the 2020 census.
Since Commerce Secretary Wilbur Ross announced in March that the constitutionally provisioned decennial census would include a citizenship question for the first time in decades, questions have arisen about how that decision was made. Documents released in response to a lawsuit from multiple states cast doubt on Ross' explanation that the question had been requested by the Justice Department to aid in enforcing voting rules, and Democrats have accused him of misleading them with his congressional testimony.
Kevin Manning, a spokesman for Ross, referred questions about the survey results to the Census Bureau, which pointed to a blog post by Ron Jarmin, the career official who is leading the bureau. (A hearing for the Trump administration's nominee to lead the Census Bureau, Steven Dillingham, was held in October, but the Senate has not yet voted on his confirmation.)
Jarmin wrote that the survey shows "misperceptions about the purpose of the 2020 Census," but he did not specifically reference findings about the citizenship question.
Distrust in government spanned ethnic groups, the researchers found. "Nearly 1 in 4 respondents fear that their answers to the 2020 Census will be used against them," their presentation shows.
Those fears are especially high among those with "low English proficiency," those who were born outside of the United States and those who responded to the survey in Spanish.
The survey is not the first Census Bureau research to raise concerns about the citizenship question. A 77-page report in August concluded that including the question "would lead to lower self-response rates in households potentially containing noncitizens, resulting in higher fieldwork costs and a lower-quality population count."