Commerce Secretary Wilbur Ross appears before the House Oversight Committee on Thursday. (J. Scott Applewhite/AP)

Commerce Secretary Wilbur Ross told members of Congress on Thursday that the 2020 Census will require significantly more funding than previously projected, in the face of anticipated low initial response rates, increased distrust of government, cybersecurity threats and technology challenges.

Testifying before the House Oversight Committee, Ross asked for an additional $3.3 billion over the $12.3 billion the Census Bureau had previously projected it would need for the 10-year life cycle of the decennial count. His request includes an additional $187 million in 2018 over the $1.5 billion the Trump administration had requested for the bureau, $800 million of which was for the 2020 count. Ross’s new estimate means 2018 spending for the count would increase to $987 million.

The constitutionally mandated decennial count determines the distribution of congressional seats, affects the shape of districts and helps decide the flow of more than $675 billion a year in federal funding.

Thursday’s hearing came as lawmakers on both sides of the aisle agree that the 2020 count is in peril. But they do not all agree on what caused the crisis or how to solve it.

At the hearing, Ross, who took office in February, blamed the Obama administration with providing “overly optimistic assessments” of how much the count would cost. But he also said that a directive from Congress that the 2020 count should not cost more than the 2010 count had compounded the problem.

Ross, a former Census Bureau enumerator, told the committee that “an efficient 2020 Census that provides a full, fair and accurate count has been one of my highest priorities since being confirmed.” But he said he knew it would also be one of his biggest challenges.

Responding to concerns about delays in the count’s communications campaign, Ross said that $500 million would be spent on communications. With the 2010 count, the bureau spent $350 million on communications, or $420 million in today’s dollars. Ross said that an additional $248 million would be spent on partnerships with community leaders and organizations, considered crucial in persuading hard-to-reach residents to fill out the survey.

The bulk of money for a decennial count is spent at the end of each decade, with 80 percent spent in the final two years of the cycle. Much of that will go to hire hundreds of thousands of temporary workers to go door-to-door to follow up with people who did not respond initially via mail or online.

At the hearing, committee members from both parties expressed concern about the success of the count.

“The Census Bureau is dangerously underfunded and has been for years, and unless we do something about it right now . . . this massive deficiency could imperil the fairness and accuracy of the census itself,” said Rep. Elijah E. Cummings (D-Md.), the ranking Democrat on the Oversight Committee. “This is not a partisan observation. Both progressives and conservatives agree that current budget projections are way, way, way too low.”

On Wednesday, Rep. Carolyn B. Maloney (D-N.Y.) introduced a bill asking for an increase in funding for the Census Bureau of $441 million over the initial 2018 Trump administration budget.

Some committee members brought up the climate of fear and anti-government sentiment among some groups, which could lower response rates and put the census at risk at a time when the bureau is already anticipating a historically low voluntary-response rate.

Asked whether he could promise these groups that their personal information would not be used for law enforcement or immigration purposes, Ross said, “My understanding is that that information is not to be used for any other purposes.”

Others questioned whether current funding is being used efficiently or whether different approaches to technology could have been tried.

“It seems to me that the Census Bureau has this attitude of, ‘We’ve got to do it ourselves,’ and aren’t looking to products that may be already out there or companies that you may be able to contract with to save some money,” such as commercial mapping and geographic information technologies, said Rep. Blake Farenthold (R-Tex.).

Ross dismissed the idea of trying new approaches at this point in the cycle. “With only having 30 months till the 2020 decennial, making radical changes would probably guarantee we didn’t get it right,” he said, adding at another point in the testimony, “I’ve been less worried about re-exploring the past than about trying to make sure we get our arms around the future.”