Why does the Trump White House want to include a citizenship question in the census next year? The administration argues the change would generate more precise data and thus prove helpful in enforcing the federal Voting Rights Act. That reasoning has been greeted by skepticism, notably by experts within the Census Bureau. They insist any gains would be dwarfed by harm in the shape of a depressed response to the census among minority groups and non-citizens.

Recall the constitutional requirement calling for an “actual enumeration” of those residing here.

Skeptics saw their argument grow stronger with the surfacing of new documents in a federal court last week. The documents are the work of Thomas Hofeller, a key figure in the extreme gerrymandering conducted by Republicans in Ohio and other states after the 2010 census. Hofeller died in August. As the New York Times recounted on Friday, his estranged daughter discovered the materials in his computer and then shared them with plaintiffs seeking to prevent the inclusion of the citizenship question.

The documents shed light on the thinking of the Trump administration. One document involves a 2015 study by Hofeller that looked at the likely partisan fallout from asking about citizenship. He found that Republicans would reap an electoral advantage due to an undercount of Hispanics. The party would be in position to craft even more extreme gerrymanders.

Hofeller argued that to get there Republicans would need more detailed citizenship data, and thus the push to ask of all census participants whether they are American citizens. He pressed the Trump transition team about including the change. Then, in late 2017, his work echoed in the formal request by the Justice Department to the Census Bureau for the question about citizenship, with the emphasis on enhancing voting rights.

Already, federal judges in the three lawsuits challenging the question have rejected the voting rights argument as plainly contrived. Wilbur Ross, the commerce secretary, has been caught in a lie. He indicated the Justice Department initiated the question. Yet the evidence shows Ross and the White House taking the lead. Now the Hofeller documents reinforce the impression of serving not voting rights but Republican Party interests.

One complication is that the Supreme Court heard oral arguments in this matter in April, with a ruling due this month. During the arguments, a majority of the justices appeared inclined to side with the administration, in particular, its contention about better enforcing voting rights. At the least, the Hofeller revelations offer reason for thinking twice.

No question, the executive has the authority to alter census questions. At the same time, the courts have the capacity under federal law to reverse actions deemed “arbitrary and capricious.” That was, in part, the reasoning at the lower court level, the voting rights argument seen as cover for a partisan result, the judges stressing, in particular, the evidence-based opposition of expert Census Bureau officials to the citizenship question.

That expertise should matter, and so should the apparent hurry. Census questions require care in their formation, including adequate testing. Thus, the law calls for Congress to receive a list of census subjects three years in advance. The White House missed the deadline, and the lower courts ruled it did not meet the test for an exception.

The larger point is that the stakes are high. The census drives no less than federal funding and the shape of congressional districts. It lays a foundation for how the country is governed. Thomas Hofeller understood as much, and his partisan instincts are at the front in the administration’s pursuit of a citizenship question — at the expense of an accurate count.