A potential showdown between the Census Bureau and the House Oversight Committee is looming after the agency refused to make top officials available for questioning about its decision to shorten the time allotted for counting every U.S. resident.

Rep. Carolyn B. Maloney (D-N.Y.), chair of the House panel, threatened to subpoena Census Bureau officials if they did not appear for interviews about plans to reduce by a month the time for going door-to-door to reach people who have failed to complete the survey. Maloney and a number of civil rights organizations say they fear the compressed time frame will lead to an undercount of Blacks and other minority communities that have been traditionally harder to count. Among the officials asked to appear for questioning were two political appointees whom Democrats have sought to remove.

“This is an urgent matter that requires immediate compliance,” Maloney wrote in a letter Wednesday to Steven Dillingham, the Census Bureau’s director. “Our investigation is critical to ensuring that the 2020 Census adheres to the constitutional requirement to enumerate every person.”

The committee set Friday as the deadline for a time to be provided for the officials to appear, but the census director has already begged off. Dillingham, noting that he appeared before the panel on relatively short notice earlier this month, said in a letter dated Aug. 7 that the Oversight Committee’s latest request was “overly burdensome.”

Allowing top census officials to sit for interviews now would create “substantial disruptions to the essential operations of the census,” especially because the count is underway and the massive effort has already been hampered by the coronavirus, Dillingham said. His letter says officials would address concerns from members of Congress during regular briefings.

“We’ve got a real problem here,” Del. Eleanor Holmes Norton (D), who represents D.C. and sits on the Oversight Committee, said Thursday. She said President Trump has declared war on the census and is politicizing the count to benefit his reelection campaign. “He does not want everyone counted,” she said.

Norton said it is important to question professional census staffers about the usual schedule and process for conducting the census and compare it with what is happening now to determine whether the population count will be accurate. She said an accurate count is of critical importance to D.C. and the surrounding region, where a rapid period of growth has appeared to slow in recent years.

“Even if you had a cooperative administration that simply wanted to count people, you’ve got [the obstacle of] the coronavirus,” Norton said. “So, you’ve got twin monsters here.”

Earlier this month, the Census Bureau reversed course on plans to extend the data collection because of disruptions caused by the pandemic. Many field operations were shut down in March, and a month later the bureau asked for additional time to complete the counting and data processing. The bureau proposed to continue field activities, such as door-knocking, until Oct. 31 and provide apportionment figures in April 2021, beyond the statutory deadline of Dec. 31. But only the House extended the deadline, and the bureau announced this month that it would cease canvassing households on Sept. 30.

The moves come as Trump has sought to change how census data is used. In 2018, his administration unsuccessfully attempted to insert a question about U.S. citizenship into the 2020 surveys. On July 21, Trump then directed the Census Bureau to exclude undocumented residents when calculating congressional apportionment. His memorandum to Commerce Secretary Wilbur Ross, whose department oversees the census, has triggered fast-tracked legal challenges by the American Civil Liberties Union and other civil rights organizations, along with several states, cities and counties.

Critics argue that Trump’s memorandum on excluding the undocumented is unconstitutional and designed to skew the census for partisan gain. His supporters say the change in calculating apportionment is overdue and necessary to correct a dilution of political power from states with high proportions of U.S. citizens to those with large populations of undocumented immigrants.

“We commend efforts by Congresswoman Maloney and her committee to try to get senior career staff from the Census Bureau to come and testify,” Sarah Brannon, managing attorney with the ACLU’s Voting Rights Project, said Thursday. “There are a lot of unknown questions about what the president’s memorandum proposes, about what the Census Bureau plans to do to respond to the memo itself and also about the change in the deadline.”