During a Senate committee hearing Tuesday, Department of Homeland Security Secretary Alejandro Mayorkas couldn’t answer a question about how many illegal immigrants federal authorities have released into the U.S. interior under the Biden administration.

Sen. Ron Johnson, R-Wis., pressed Mayorkas on the issue, but the DHS secretary couldn’t provide a number at Tuesday’s Senate Homeland Security and Governmental Affairs Committee hearing. Illegal immigration at the southern border of the U.S. has surged past 2 million in both fiscal year 2022, the highest year on record, and 2023, according to federal data.

An inspector general report in September found that DHS lacks the ability to track all illegal immigrants released from its custody into the U.S. interior, partially because of the overwhelming surge at U.S. borders.

“I’ve asked you this in the past, what numbers are represented here? How many people has this administration let in by encountering, processing, dispersing or that come in as a known or an unknown ‘gotaway’? Approximately, I don’t need an exact number, so what do we got?” Johnson asked Mayorkas.