A union representing 12,000 U.S. Citizenship and Immigration Services officers will publicly oppose the Senate Gang of Eight immigration plan Monday, giving critics of the overhaul effort additional political ammunition as they work to defeat legislation working its way through the Senate Judiciary Committee.

In a release announcing the group’s opposition to the bill, National Citizenship and Immigration Services Council president Kenneth Palinkas writes that the bill would fail to address an “insurmountable bureaucracy” at the federal agency overseeing immigration documents and argues that USCIS personnel are currently “pressured to rubber stamp applications instead of conducting diligent case review and investigation.”

“The culture at USCIS encourages all applications to be approved, discouraging proper investigation into red flags and discouraging the denial of any applications,” he wrote in the release.