WASHINGTON – As the 2020 census struggles to find its footing amid the coronavirus outbreak and public reluctance to give the government personal data, officials have a new worry: The Trump administration and Senate Republicans appear to be signaling that they want the census finished well ahead of schedule, pandemic or not.

With almost 40% of the nation's households still uncounted, including the hardest-to-reach populations that are disproportionately poor, people of color and young, the Trump administration took the Census Bureau by surprise last week. It asked the Senate Appropriations Committee to set aside $448 million in the next coronavirus relief package for a "timely" completion of the census.

The request did not define what "timely" meant, and legislation released Monday said only that the money would be used for nationwide census operations and data processing. But it comes as census workers and former officials say the White House and the Commerce Department, which oversees the Census Bureau, are asking how the bureau can compress its schedule to wrap up the count of households earlier than expected — perhaps by the end of September. The aim, they say, may be to speed up the delivery of key data for political reapportionment to the president by the end of December.

The administration has yet to announce a compressed schedule and may not find a way to do so. But the prospect already has alarmed an array of experts, who warned in recent days that an expedited census risks a deeply flawed count of the nation's population. The census is constitutionally required to count all residents of the country every 10 years.

"There's a lot of uncertainty, but one thing is absolutely sure: There will be egregious undercounts if the Census Bureau has to produce this data by December," said Robert Santos, vice president of the Urban Institute and incoming president of the American Statistical Association.

Some, including former Census Bureau directors, raised the prospect that the final totals could be so skewed that a future Congress might order the bureau to do further work on the 2020 population data or even consider another census in five years, which federal law allows but which has never been conducted nationwide.

The numbers are enormously important. They are used to reapportion all 435 House seats and thousands of state and local districts, as well as divvy up trillions of dollars in federal grants and aid.

At issue is how fast, and how precisely, the Census Bureau will track down and count the 60 million households that have not filled out census forms.

Slightly more than 6 in 10 households have completed forms. The remainder are the very hardest to count. To reach them, the bureau has planned to deploy up to 500,000 census takers, each with an iPhone that can securely relay census data to the bureau's computers.

In 2010, census takers worked from May to August to count hard-to-find households. This spring, with the start of that count delayed by the pandemic, the bureau said it was pushing back the start of that work to August, ending Oct. 31.

With White House approval, the bureau also asked Congress for a four-month extension — to April 2021 — of the Dec. 31 statutory deadline for delivering to the president the population totals required to reapportion the House of Representatives.

But that plan now appears to be in flux. Census Bureau workers have been asked whether that Oct. 31 deadline for collecting data can be moved to September, giving them six or seven weeks to finish a count that was supposed to take 10 weeks.

At the same time, the administration's commitment to extending the delivery of reapportionment statistics beyond the statutory Dec. 31 deadline also appears in doubt.

In Congress, the House has approved the four-month delay. The Senate has not.

The White House declined to address questions about its census plans. Responding to a reporter's questions, the Census Bureau issued a statement Monday that neither confirmed nor denied an effort to hasten the completion of the count and the delivery of reapportionment figures. In fact, top Census Bureau officials already have said that meeting that deadline is impossible.

"We have passed the point where we could even meet the current legislative requirement of Dec. 31. We can't do that anymore," the census official leading field operations for the count, Tim Olson, told a Native American organization during a webinar in May.

And in a webinar this month for groups with a stake in census results, the associate director of the census, Albert E. Fontenot Jr., said, "we are past the window of being able to get those counts" by year's end.