The spread of the coronavirus has ravaged businesses, closed schools, and wreaked havoc upon the lives of most people in the United States. But it is presenting a unique challenge to the Census Bureau.

Census officials have spent a decade planning for the coming months. Under the best of circumstances, it was always going to be a challenge to count hundreds of millions of people and to try and figure out where they lived as of Wednesday. But the spread of the coronavirus has added a really big hurdle.

The stakes for ensuring an accurate count are extremely high. The census count is what’s used to determine how many representatives are apportioned to each state, which in turn sets the number of votes that the states get in the Electoral College in the 2024 and 2028 elections. The numbers will also be used by federal agencies to allocate spending on government programs.

Under normal circumstances, the process would begin with the Census Bureau sending notifications for individuals to fill out their forms online, by phone, or by mail. (Online is easiest, by the way — it takes less than 10 minutes.) Those who don’t respond are sent follow-up reminders. Eventually, an army of census workers knocks on tens of millions of doors to attempt to reach those who have failed to respond.

That’s where things get tricky. During a time when the health officials are advising in favor of severe social distancing, how could the government simultaneously be dispatching so many census takers to do follow-up visits? In some cases, census workers are asked to visit the same households up to a half a dozen times.

The Census Bureau has already taken some actions to adjust to the coronavirus. At this point in the process, field operations would be starting to interview people in remote locations, but that’s been suspended, and the deadline has been extended by two weeks. Follow-up visits with households that did not self-respond, which were supposed to start in early April, have now been pushed back a month, to early May. The final deadline for responses has also been pushed back from July 31 to Aug. 14.

There have been calls for the census to delay operations even further, but that makes things trickier still. This isn’t merely like postponing a sporting event or even the Olympics. The U.S. Constitution specifies that after the initial Census of 1790, there must be population counts “within every subsequent term of ten years, in such manner as [Congress] shall by law direct.”

So while the method of conducting the census may change, the timing is almost written in stone. It’s possible that census officials can make further adjustments to the schedule, but there are limitations. They need to be able to conduct the count within 2020.

Given current delays, census officials still anticipate they will be able to deliver state population totals to the president by Dec. 31, which will determine the number of representatives, and local data to the states by April 1 that will be needed to handle redistricting ahead of the 2022 elections.

So, even if there is some more wiggle room, there are limits.

All of this heightens the importance that everyone receiving a census notification do their part to minimize the need for follow-up visits. In just five to 10 minutes, anybody can complete the basic census form online, by phone, or by mail. The higher the initial response rate, the fewer follow-up visits will be required. This will help reduce the potential for census workers to spread the coronavirus and make this crisis more manageable for those officials tasked with ensuring an accurate count.