The Census Bureau defended its plan to delay the delivery of detailed results from the 2020 census during a Senate hearing Tuesday, amid Republican concerns the postponement would scramble efforts to redraw legislative maps.

Democrats on the Homeland Security and Governmental Affairs Committee largely backed the Biden administration plan to deliver apportionment data by the end of April and redistricting data by September.

But committee Republicans pressed acting Census Bureau Director Ron Jarmin over delays to the redistricting data, asking why the agency could not prioritize certain states or have provided earlier notice about the late delivery.

Sen. James Lankford, R-Okla., said the delays will “create an enormous litigation nightmare” for states like his, which will blow past a state constitutional deadline to draw new legislative maps.

Sen. Rob Portman, R-Ohio, urged the Census Bureau to add more staff to the process, calling it “nonsensical” when Jarmin responded that training new staff would only add to delays. Ohio has sued in federal court to try and force early release of the figures.

“We have constitutional requirements that may lead us to not be able to use your data, which is just unheard of,” Portman said.

Jarmin defended the steps the Census Bureau has taken to wrap up the count, and said the agency may be able to deliver some data in an outdated format sometime in August.

“We’re trying to get the data to the states as quickly as we can,” he said.

This year marks the first time the agency will miss its current March 31 statutory deadline to deliver apportionment and redistricting data. Officials said the delay comes from a combination of snags in processing and a Trump administration decision to prioritize apportionment data in an effort to finish the count by the end of last year.

The Census Bureau halted many in-person aspects of the decennial count last year due to the coronavirus pandemic. Its counting efforts also were scrambled by natural disasters, decisions by the Trump administration and the mass movement of college students who left campus because of the pandemic.

A Government Accountability Office report released Monday found the Census Bureau largely made up time from the delay, but ran into problems with counting people in areas affected by wildfires and hurricanes. In particular, the agency could not reach more than 20,000 households in the Shreveport area of Louisiana.

The agency is currently facing several lawsuits over the conduct of the census, including two from Ohio and Alabama that call for the early release of census data. Alabama has sought to fast track its lawsuit over the issue, which the Justice Department opposed in a filing Tuesday. In the court document, the DOJ said the state cannot shoehorn arguments over privacy protections or the delay into a statute meant to handle disputes over statistical methods.

Sen. Brian Schatz, D-Hawaii, has said he plans to reintroduce a bipartisan bill to extend the census deadlines, allowing the agency to complete its work by the end of September. A similar measure passed the House last Congress but was not taken up by the Republican-controlled Senate.

Senate Homeland Security and Governmental Affairs Chair Gary Peters, D-Mich., has backed the agency’s plan for a delayed delivery and said he tried to pass legislation on that point last Congress.

“The bureau faced incredible challenges to this mission in 2020. And now we must work together to finish the 2020 census and ensure that it is a success,” Peters said.

Commerce Secretary Gina Raimondo backed giving the Census Bureau more time during her confirmation hearing earlier this year. Biden has not yet named a permanent head for the agency after former director Steven Dillingham left days before the end of the Trump administration.