The Obama administration should have been more transparent about its secret telephone data collection programs, Democratic Sen. Mark UdallMark Emery UdallSenate GOP rejects Trump’s call to go big on gun legislation Democratic primary could upend bid for Colorado seat Picking 2018 candidates pits McConnell vs. GOP groups MORE (Colo.) said Sunday.

"I expect the government to protect my privacy. And it feels like that isn't what's been happening," Udall said on CNN's "State of the Union." "Again, there's a line, but to me, the scale of it and the fact the law was being secretly interpreted has long concerned me. I'm glad we're having this debate. I'm very worried, by the way, about the leaks. I abhor leaks.

"I wish the administration had been more transparent," he continued. "This is an important discussion. We value our privacy as Americans. It's a part of our freedoms and liberties."

Udall's comments come after the disclosure of a National Security Agency surveillance program that collects metadata on phone calls, including numbers and the location and duration of calls. 

The Obama administration defended the surveillance as necessary for national security, but critics said it was an overreach that violated the privacy of millions of Americans not suspected of wrongdoing.

In the same interview Udall expressed skepticism that the phone data collection operation and a separate program that collects internet information is the only way to thwart terrorist plots. 

"My concern is that this is vast. It hasn't been proven that it works, uniquely. It hasn't been proven to have disrupted plots," Udall said.