The Founding Fathers must be spinning in their graves.

Not because of cavalier threats about nuclear apocalypse and attempted erosion of First Amendment rights (OK, maybe those things, too). Because our federal government is failing to execute one of its most basic constitutional duties: the decennial census.

The decennial census is the country's largest civilian mobilization. It determines where billions of federal dollars flow each year, and how many congressional and electoral college seats each state gets. The results have enormous influence over the decisions of businesses and local governments, too.

It's also, yes, mandated by the U.S. Constitution, right there in Article I, Section 2.

Yet despite all the brandishing of pocket Constitutions on the right, the Trump White House and Republican lawmakers are sabotaging this sacred mandate. First they refused to sufficiently fund it. Now they're taking actions that would severely depress participation.

This raises the prospect that those final, critically important numbers will be — to use one of our president's preferred adjectives — WRONG.

You might be thinking: It's only 2018! The census is a couple of years off. We have time to get it right.

While the enumeration itself doesn't happen until 2020, planning begins years in advance. The Census Bureau must try out questions. It must test-drive technologies — especially important this time around, because for the first time, the questionnaire will be administered primarily online.

The bureau must also figure out which community groups can help with public outreach and what kind of messaging will be most effective in getting people to stand up and be counted.

This last task is especially challenging in an era marked by record distrust of government. (More on that in a bit.)

Already, funding shortfalls and administration disorganization have left these efforts woefully behind.

A scheduled dress rehearsal for the 2020 count was whittled from three sites to one, in Providence County, Rhode Island.

One goal of such tests is to find ways to maximize participation of "hard-to-count" populations, such as immigrants, the homeless and households below the poverty line. Because these are largely Democratic constituencies, Republicans may shrug at the setbacks they've created.

But Trump Country is also at risk at being overlooked.

That's because funding uncertainty forced the Census Bureau to kill its "only opportunities to test, in a real-time, census-like environment, special counting methods for rural areas," as Vanita Gupta, president of the Leadership Conference on Civil and Human Rights, explained in recent congressional testimony.

Apparently not content to shortchange funding, the administration is also taking steps that will actively decrease participation.

As ProPublica first reported, the Justice Department recently sent a letter to the Census Bureau asking it to add a new question to the 2020 form. Adding a question — any question — this late in the game is risky; there's no time to field-test how people will respond to it.

But this particular question is unusually hazardous: It's about citizenship.

The Justice Department claims it needs finely grained citizenship data to enforce the Voting Rights Act, a proposition that every census alumnus and civil rights expert I interviewed rejected.

Whatever the administration's motives, the main consequence of adding this question is clear: It would spook immigrants (legal or otherwise) and especially Hispanics anxious about how the government might use their data.

In unrelated survey testing last year, respondents fretted about what would happen to information they gave to the Census Bureau. Unprompted, some mentioned the "Muslim ban," "discomfort 'registering' other household members" and fears that immigration authorities would come after them. Some falsified names and dates of birth.

Those survey respondents were paid, too, suggesting they'd be more likely to cooperate than would the general population.

"The politics have changed everything. Recently," one field representative explained, according to a Census Bureau memo.

In a statement, the bureau said it was still "evaluating" the Justice Department request. Even if the Census Bureau ultimately leaves this question off the form, though, the reputational damage may already be done. Significant undercounts could distort how dollars and congressional seats are divvied up. Likely (and perhaps not coincidentally) to the advantage of Republicans and their constituencies.

The Constitution requires the decennial census to count all people, not just all citizens. Commerce Secretary Wilbur Ross, whose department oversees the census, seems to truly want to produce a full, accurate, nonpartisan count, not least because the business sector wants one.

But in an era of data trutherism and political tribalism, Republican lawmakers and the rest of the administration appear to have other priorities.

Catherine Rampell's column is distributed by the Washington Post Writers Group.