President Trump’s nominee for director of the Census Bureau acknowledged Wednesday in his Senate confirmation hearing that there was a “possibility” that the inclusion of a citizenship question in the 2020 census could affect participation in the survey – but he refused under questioning to take a position on whether the question should be added to the census.

Steven Dillingham was asked by Sen. Maggie Hassan (D-NH) — a member of the Homeland Security and Governmental Affairs committee, which is considering Dillingham’s nomination — whether he agreed with the assessment by several experts that the question could hurt participation rates.

“The Census Bureau has had its best and brightest look at this, and they have identified the possibility that there could be changes in responses,” Dillingham said. “If there are those changes and if we don’t get the immediate responses that we would like and anticipate, there are follow-up activities to collect that information.”

The decision to add the question was made not by the Census Bureau, which has been led by a career official in an acting capacity since Trump took office, but rather by Commerce Secretary Wilbur Ross, who has oversight over the decennial survey.

Policy experts and civil rights advocates have raised concerns that the citizenship question will spook immigrant communities from participation, and that political power and and federal funding will be shifted from those populations due to such an undercount. Litigation over the question has revealed that top experts within the Census Bureau flagged the risk of an inaccurate count and other issues about the question to Ross before he added it.

Sen. Steve Daines (R-MT), a proponent of adding the question, asked Dillingham his views on the citizenship question.

“I have no plans to voice an opinion on that question,” Dillingham said, pointing to the ongoing lawsuits seeking to remove the question.

“The decision will be determined by the courts,” Dillingham said, adding that it would then be his responsibility to implement the court’s decision. He said it that it would thus would be”problematic” for him to take a position on that question.

Sen. Kamala Harris (D-CA) also grilled Dillingham about the citizenship question. She asked first hypothetical questions about how Dillingham believed new questions should be studied before being added to the census, as well as how Dillingham would handle a situation in which a political appointee asked him to redesign a question in a way that census experts believed would make the survey less accurate.

He promised to “push back if I think it was improper influence.”

Harris then pointed out that a number of experts — both currently within the bureau and former directors of both parties — believe the citizenship question will deter participation.

“I have seen the public analysis and the presentation of options that were part of the decision making, and I am aware that there’s a number of views with regard to potential impact, possible impact,” Dillingham said.