The 'Gang of Eight' immigration proposal has a number of elements that offer a path to legal residence for the millions of people here without documentation. But the plan calls for a pre-requisite: That the borders must first be secure.

McCain went on to stress the importance of using high-tech measures. For one, the U.S. already has a small fleet of drones patrolling the Mexican border.

We're joined now by Ander Becker of the Center for Investigative Reporting, who covers border and national security issues.