A White House draft executive order proposing to restrict foreign worker visas and target immigrants who get federal aid also recommends that the U.S. Census ask about immigration status, a change that experts said could have far-reaching consequences not only on immigrants but also on local economies and political redistricting.

Annual questionnaires from the Census Bureau already ask whether respondents are citizens. But probing into the status of those who are not would be new, and Census experts say it would have a detrimental effect on future counts.

“It will drive the response rate down enormously,” said Kenneth Prewitt, a former director of the Census Bureau who is now a professor of public affairs at Columbia University. Immigrants here illegally are unlikely to answer questions about their status, he said, adding that the resulting undercount could have chilling effects.

“If you drive those people out of the Census, the consequence is that they’re not in it,” he said. “It’s a step toward not counting the people you don’t want to count. And that goes very far in redrawing legislative boundaries.”

The draft, entitled, “Executive Order on Protecting American Jobs and Workers by Strengthening the Integrity of Foreign Worker Visa Programs,” proposes that the director of the U.S. Census Bureau “include questions to determine U.S. citizenship and immigration status on the long-form questionnaire in the decennial census.”

It is not clear which questionnaire is being referred to; the decennial Census, taken every 10 years, used to include a long-form questionnaire for some respondents, but it was abandoned in 2000 in favor of the annual American Communities Survey.

However it is presented, asking about immigration status would undo decades of work to convince immigrants and communities of color to fill out the forms, said Steve Jost, who was head of communications for the Census in 2000 and 2010.

A lower response rate would also make the Census more expensive, as more workers would be needed to be hired to go out to find non-respondents. “It’s an ironic move, because the whole conversation about the 2020 Census has been to reduce the cost,” he said. In 2010 the bureau spent $2.5 billion for follow-up to non-responding households.

The recommendation comes at a time when many are already worried that government data collection and record-keeping will be at risk under the Trump administration. Scientists spent the weeks leading up to his inauguration frantically backing up climate change data in fear that the incoming administration would remove them.

It also comes at a time of waning confidence in such data among some voters. More than half of Trump voters said they do not trust government data about the economy.

The draft is one of a couple circulating among administration officials which the Washington Post obtained copies of. The White House would not confirm or deny their authenticity and White House officials did not respond to requests for comment on them Monday, Tuesday or Wednesday. Census officials did not return a call for comment on Wednesday.

The Census is mandated by the Constitution, and some form of the American Community Survey has been used since 1850. The results are used by the government to allocate federal funding to states and local areas for schools, health care, roads, housing, and law enforcement, and by companies and entrepreneurs to make business decisions.

For recent counts, advertisements have sought to reassure people in immigrant communities that filling out Census forms would not endanger them. “No INS, No FBI, No, CIA, No IRS,” read a poster in bodegas and unemployment offices that vowed the bureau would not share personal information with any other agency.

That promise is codified in Title 13, a 1954 law that forbids Census employees for life from sharing such information; those who disobey face punishments of up to $250,000 fine and five years in prison. The law was not in effect when the Census Bureau helped the government identify where Japanese-Americans lived.

The Bureau came under criticism in 2004 after it was revealed to have shared data with the Department of Homeland Security on where Arab Americans lived by city and Zip code.

Proposals to ask about immigration status have been floated in the past, but immigration advocates fear that this time there is a better chance that such a rule would be adopted.

Communities with undercounted populations would also suffer economically, Prewitt said; for example, a town might need to have 50,000 residents to justify building a big box store. “Anyone who cares about the size of population in their locale will suffer from this,” he said. “We can only hope that mayors and other [local officials] will fight back.”

Terri Ann Lowenthal, a former staff director of the House Census oversight subcommittee, said the proposal is troubling to Census stakeholders, including business and industry leaders, state and local officials, civil rights advocates, and scientists.

“I don’t think this proposal is well-thought out,” she said, noting the lack of clarity as to which questionnaire it refers to. Even if the president does not take it up, she said, “Stakeholders are worried that it can trigger an effort by one or more members of Congress to require the Census Bureau to add a question on citizenship and immigration status to the 2020 Census.”

Although that survey is three years away, the bureau has already spent seven years and hundreds of millions of dollars testing and refining questions for it, and a late change of this type would undermine those efforts, she said.

Jeff Miller, vice president for communications at The Leadership Conference on Civil and Human Rights, also blasted the plan, saying, “We strongly urge the administration to consult with knowledgeable scientists at the Census Bureau and the incoming Commerce Secretary about damage this would do before moving forward with this ill-advised proposal.”