The Census Bureau will miss a year-end deadline for handing in numbers used for divvying up congressional seats, a delay that could undermine President Donald Trump’s efforts to exclude people in the country illegally from the count if the figures aren’t submitted before President-elect Joe Biden takes office.

The Census Bureau plans to deliver a population count of each state in early 2021, as close to the missed deadline as possible, the statistical agency said in a statement late Wednesday.

“As issues that could affect the accuracy of the data are detected, they are corrected,” the statement said. “The schedule for reporting this data is not static. Projected dates are fluid.”

It will be the first time that the Dec. 31 target date is missed since the deadline was implemented more than four decades ago by Congress.