Steven Dillingham, the director of the US Census Bureau who has faced criticism from Democrats who say he has politicized the agency, announced he will resign on Wednesday at the end of President Donald Trump’s term.

The Census Bureau is in the middle of crunching the numbers for the 2020 census. Democratic lawmakers last week called on Dillingham to resign after a watchdog agency said he had set a deadline that pressured statisticians to produce a report on the number of people in the U.S. illegally.

“Many institutions demurred in the face of this pandemic, and it is easy to understand why,” Dillingham wrote in a letter to staff. “But you did not. You met this challenge head on and overcame it. You adapted operations to carry out the mission while following public health and safety protocols. You made great sacrifices to continue our work as you and your loved ones experienced the pandemic. You were resilient and persevered.”