The director of the U.S. Census Bureau on Wednesday indefinitely halted efforts to comply with President Donald Trump's order demanding data on who is in the country illegally after receiving blowback from civil rights groups and concerns raised by bureau statisticians about the accuracy of such figures.

Bureau workers laboring to comply with the presidential order were instructed to “'stand down' and discontinue their data reviews," Census Bureau Director Steven Dillingham said in a memo.

Dillingham's memo came after the Office of Inspector General reported Tuesday that bureau workers were under significant pressure from two Trump political appointees, Nathaniel Cogley and Benjamin Overholt, to figure out who is in the U.S illegally using federal and state administrative records. Dillingham had set a Friday deadline for bureau statisticians to provide him a technical report on the effort, the inspector general's memo said.

After the release of the inspector general's memo, a coalition of civil rights groups called for Dillingham's resignation, saying he was undermining the statistical agency's standards for data quality to comply with Trump's order, which was “motivated by partisan objectives."

“We do not lightly come to the conclusion that he should resign,” leaders of the National Association of Latino Elected and Appointed Officials, Asian Americans Advancing Justice and The Leadership Conference on Civil and Human Rights said in a statement. “Dillingham’s order to divert precious staff time away from producing the apportionment count and into producing data on citizens and noncitizens for political, partisan purposes is a betrayal of the mission of the Bureau."

Census Bureau directors have five-year terms and Dillingham's tenure does not end until the end of the year.

The appointments of Cogley and Overholt last year were highly criticized by statisticians, academics and Democratic lawmakers, who worried they would politicize the once-a-decade census.

Trump two years ago ordered the Census Bureau to use administrative records to figure out who is in the country illegally after the Supreme Court blocked his administration’s effort to put a citizenship question on the 2020 census questionnaire. The statistical agency has not publicly said what method it’s utilizing to do that.

Information about the citizenship status of every U.S. resident could be used to implement another Trump order seeking to exclude people in the country illegally from the count used for divvying up congressional seats and Electoral College votes, as well as the annual distribution of $1.5 trillion in federal spending, among the states.

An influential GOP adviser had advocated excluding them from the apportionment process in order to favor Republicans and non-Hispanic whites. Trump’s unprecedented order on apportionment was challenged in more than a half-dozen lawsuits around the U.S., but the Supreme Court ruled last month that any challenge was premature.

The ability to implement Trump’s apportionment order is in jeopardy since the processing of the data is not scheduled to be done until early March, many weeks after Trump leaves office and President-elect Joe Biden is sworn in Jan. 20. Biden has said he opposes the effort.

The whistleblowers told the Office of Inspector General that the Census Bureau has not set rules for categorizing the citizenship status of U.S. residents. Bureau statisticians also do not fully understand the data since portions came from outside the bureau and they are worried incomplete data could be misinterpreted, they said.

“One senior Bureau employee went as far to say that this work is statistically indefensible," the Inspector General's memo said.

Robert Santos, the president of the American Statistical Association, on Wednesday praised the whistleblowers for coming forward with their concerns.

“If such data must be generated, they should be of the highest quality," Santos said. “Forcing the Census Bureau to generate faulty data for the sake of an arbitrary deadline goes against the Bureau’s commitment to scientific integrity and would do immeasurable harm to its reputation as a world class statistical operation."

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Follow Mike Schneider on Twitter at https://twitter.com/MikeSchneiderAP.