Automatic spending cuts due March 1 could pose a real setback for immigration reform by forcing the Border Patrol to reduce its workforce hours by the equivalent of 5,000 agents beginning in April — a nearly one quarter reduction.

That’s the upshot of testimony by Homeland Security Secretary Janet Napolitano submitted to the Senate Appropriations Committee Thursday.

The 5,000 number is the most detailed public assessment yet by her department and comes just days after President Barack Obama underscored the importance of border security in his State of the Union address.