Colorado Sen. Mark Udall called the National Security Agency’s phone surveillance program “close to being unconstitutional,” arguing Sunday that “there’s a better way” to protect against terrorist attacks without infringing Americans’ privacy.

Appearing on CBS’ Face the Nation, Udall, a Democrat, warned that “the NSA is literally collecting every phone record of every American, every day.” Although the NSA is not authorized to listen to those phone calls, the collection of that data represents a “violation of your privacy,” Udall said.