SINCE THE Supreme Court blocked President Trump from manipulating the census — the constitutionally mandated decennial count of every resident — it has been easy to assume that the danger to the count’s integrity has passed. But the census, which is to begin in earnest in April, is not in the clear, according to a report the Government Accountability Office (GAO) released Wednesday.

The stakes are high: Census numbers determine where $1.5 trillion in federal spending goes and how congressional seats are distributed among the states. The count must be accurate. The GAO found that the census was able to complete its initial stages, including an operation to check and update millions of addresses. But it is behind on staffing up for the big count. The bureau was supposed to recruit 2.5 million people by early February, but it fell short by about 400,000 recruits. Similarly, the census relies on “community partners” — civil society organizations such as churches, health-care groups and media outlets — to educate Americans about when, how and why to complete their census forms. The bureau is behind its own goals in recruiting these partners, too.

Perhaps most alarming in the wake of the Iowa caucuses vote-counting flop, not to mention the 2013 healthcare.gov fiasco, the GAO warned that several important digital systems may not be ready by the time the census effort ramps up in April. The bureau recently switched to a backup electronic census form collection system, a late change that raised the GAO’s concern. In previous years, this might not have raised such a red flag. This year, the bureau will encourage people to submit their census forms electronically, and enumerators will use mobile apps while out in the field. It is more important than ever that the digital systems work.

In Wednesday testimony before the House Oversight Committee, census officials predicted that they would meet, even surpass, their recruiting goals and that IT systems will be properly tested in time. But Christopher Mihm, the GAO’s strategic issues managing director, warned that the bureau still risks “delays, increased costs and eroded data quality.” He noted that the task is massive: If 60.5 percent of households respond to the bureau’s initial solicitations, the bureau will still have to follow up with 61 million households. If the response rate is only 55 percent, 66.7 million will require follow-up.

An underlying concern about the bureau’s preparedness is the fear that some communities will be counted and others neglected, leading to distortions in the distribution of federal benefits and congressional representation. Poor and minority communities that are harder to reach could suffer. Immigrants wary of sending any information back to a Trump-run federal government may be more difficult than usual to count. Then there is the toll that simple confusion will take. The Republican National Committee recently increased the likelihood that people will be baffled by the census process when it sent out official-looking “2020 Congressional District Census” forms that contained anti-Democratic Party propaganda and a fundraising appeal.

The census, one of the few functions the Constitution mandates for the federal government, should be sacrosanct. That applies as much to the politicians who have sought to take advantage of the process as it does to the officials the country is depending on to conduct a sound count.

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