Measuring border security to achieve 90 percent effectiveness is required as part of the path to citizenship for the country's estimated 11 million illegal immigrants, the Los Angeles Times reported Wednesday.
The proposed legislation gives the Border Patrol five years to demonstrate it can capture or turn back 90 percent of the people who illegally attempt to enter the country across the Southwest border.
The bill provides $4.5 billion to add patrol agents, fences, surveillance drones, advanced radar and other equipment.
U.S. Sen. John McCain, R-Ariz., is among the eight senators who put the immigration deal together.
"I am confident that the technology and surveillance capability as well as the drones will allow us to have effective control of the border, McCain said.
His negotiating partner, Sen. Charles E. Schumer, D-N.Y., said supporters insisted concrete metrics be achievable.
Border residents, experts and longtime patrol agents have expressed deep skepticism, the Times reported.
They want to know how anyone can reliably estimate the number of immigrants that agents don't catch in order to prove 90 percent effectiveness.