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.

“There are apps you can get on your smartphone and your smart tablet or your computer that can take that data and give a pretty good impression of what you do during your daily activities,” Udall said. “To me, that is a violation of Americans’ privacy.”

The House last week defeated an effort to defund the NSA’s telephone monitoring program led by Rep. Justin Amash, R-Mich. The vote shook up party lines, with Democrats and Republicans voting both for and against.

Udall is promoting a bill to limit the ways in which the NSA and other intelligence agencies can access Americans’ phone records, requiring them to gain approval from a Foreign Intelligence Surveillance Act court. “That’s the way to go forward, that’s the way to protect – not just our people, but the Bill of Rights,” Udall said. “The Bill of Rights is the biggest, baddest weapon we have.”

House Intelligence Committee Chairman Mike Rogers, R-Mich., on the same show strongly defended the NSA program, calling it a “real success” in preventing terrorist attacks.

“You’re taking away the one tool that we know will allow us that nexus between a foreign terrorist overseas talking to someone in the United States,” Rogers warned. “It’s saving real lives. Real folks have come home with their legs, real folks have had their lives not taken coming home from work because of this program.”

Rogers denied that the program represented a threat to Americans’ civil liberties and touted its successes, saying that “there’s zero privacy violations on this, in its entire length of the program, and 54 disrupted terrorists plots.”

Rogers cautioned that no other government program faces so much public scrutiny for processing so little information.

“There’s more information in a phone book than there is in this particular big pile of phone numbers,” Rogers said, claiming that the program has allowed the U.S. to close the intelligence gap that failed to detect the Sept. 11, 2001 terrorist attacks.