HERE IS one of the least surprising revelations ever leaked from the federal government: According to an internal Census Bureau document, major, uncorrectable errors may result from forcing the bureau’s enumerators and number-crunchers to rush through the decennial count. House Oversight and Reform Committee Chair Carolyn B. Maloney (D-N.Y.) revealed the document this month, claiming it was a presentation for Commerce Secretary Wilbur Ross, who oversees the bureau. It shows that the decision of Senate Republicans and the Trump administration to give the bureau no more time to finish a count that started late and has encountered pandemic-related problems threatens to corrupt for a decade the process of distributing congressional seats and doling out some $1.5 trillion in annual federal aid.

“A compressed review period creates risk for serious errors not being discovered in the data — thereby significantly decreasing data quality,” the document warns.

To be clear, this would not be the fault of the bureau’s professionals, whom Republicans have put in an impossible position. They are facing a statutory deadline requiring that they deliver their count by Dec. 31. The bureau had previously asked for more time. House Democrats authorized a deadline extension. Senate Republicans failed to do so, and the Trump administration ordered last month that door-knocking conclude by Sept. 30, weeks earlier than the experts had hoped.

The newly revealed document shows that, at the time the short timetable was announced, the bureau knew that “abbreviated processes or eliminated activities . . . will reduce accuracy.” Not only would door-knocking end weeks sooner, but also the number-crunching needed after the door-knockers finished their work would be compressed into 92 days. Since 1990, the number-crunching has consumed between 140 and 185 days, according to Ms. Maloney. “Serious errors discovered in the data may not be fixed — due to lack of time to research and understand the root cause or to re-run and re-review one or multiple state files,” the document warns. “A compressed review period creates risk for errors being present in the data.”

The only perspective from which this is not a potential disaster is that of Republicans seeking maximum partisan advantage. The Trump administration already tried once to skew the count by adding a citizenship question to the census form, which would have deterred immigrants, even legal ones, from responding. The Supreme Court halted that move. Yet rushing the census might help Republicans because poor and minority communities tend to be the ones undercounted, which would make many Democratic-leaning states appear to be less populous than they are — and therefore due less money and political representation.

The Senate should have passed a covid-19 relief bill months ago, with a census deadline extension in it. With the bureau up against a wall, senators should not wait to agree on the rest of a relief package to give the counters more time. The census needs clarity, now.

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