Despite all that, the NSA has maintained support where it needed it most: at the White House and among key congressional leaders.

Snowden, in the Washington Post interview in which he made his victory claim, said his only goal was to create a public debate about the NSA and its powers.

"I didn't want to change society. I wanted to give society a chance to determine if it should change itself," he said. "All I wanted was for the public to be able to have a say in how they are governed."

But civil liberties advocates are openly frustrated.

Mark M. Jaycox, an analyst with the Electronic Frontier Foundation, a San Francisco-based privacy advocacy group, says he is disappointed because Obama had criticized NSA surveillance activities when he was a senator.

Now "we have a President Obama who has witnessed the bulk collection [of domestic telephone data] and sees just how much information is being collected," Jaycox said. "And yet he continues the program."

Many privacy advocates, conceding that they have made little progress in this round, hope to do better next year.

The provision of the Patriot Act that allows the NSA to amass telephone metadata expires in June 2015. Because the agency's authority will end if no new legislation passes, backers of the intelligence agency will have the burden of persuading their colleagues to vote to keep it in place.

"Public opinion is moving our way," said Sen. Ron Wyden (D-Ore.), one of the leading congressional critics of the NSA. "More and more people think that security and liberty are not mutually exclusive."

Christi Parsons and Michael A. Memoli in the Washington bureau contributed to this report.