"We are open to re-evaluating this program in ways that can perhaps provide greater confidence and public trust that this is in fact a program that achieves both privacy protections and national security," Robert Litt, counsel to the Office of the Director of National Intelligence, told skeptical members of the Senate Judiciary Committee.
The hearing came one week after a surprisingly close vote in the House that would have killed the phone surveillance program. It barely survived, but lawmakers promised that change was coming.
This newest privacy-vs.-collective security debate was touched off when former government contract systems analyst Edward Snowden leaked classified documents exposing National Security Agency programs that store years of phone records on every American. That revelation prompted the most significant reconsideration yet of the vast surveillance powers Congress granted the president in the wake of the harrowing Sept. 11, 2001 terrorist attack.
On Wednesday, the national security establishment sought to reassure Congress that their surveillance powers were rigorously monitored and narrowly crafted while simultaneously leaving open the possibility of some new limitations.
To that end, the administration declassified documents about the telephone program. But the documents revealed no legal analysis that underpinned the widespread surveillance. And the redacted documents show only in broad strokes how NSA officials use the data.
For the first time, however, the government acknowledged publicly that using what it calls "hop analysis," it can analyze the phone calls of millions of Americans in the hunt for just one suspected terrorist. That's because NSA analysts can look at not just a suspect's phone records, but also the records of everyone he calls, everyone who calls those people and everyone who calls those people.
If the average person calls 40 unique people, three-hop analysis could allow the government to mine the records of 2.5 million Americans when investigating one suspected terrorist.
"What's being described as a very narrow program is really a very broad program," said Sen. Richard Durbin of Illinois, the No. 2 Democrat in the Senate.
John Inglis, the NSA's deputy director, conceded the point but said, in practice, such broad analysis was rare.
"We have to compare the theory to the practice," he said.
Last week's House vote of 217-205 defeating an attempt to dismantle the program was significant not only because of the narrowness of the victory for the Obama administration, but also because it created unusual political coalitions. Libertarian-leaning conservatives and liberal Democrats pressed for change against the Republican establishment and Congress' national security experts.
Backing the NSA program were 134 Republicans and 83 Democrats, including House Speaker John Boehner, R-Ohio, who typically does not vote, and Democratic leader Nancy Pelosi. Rejecting the administration's last-minute pleas to spare the surveillance operation were 94 Republicans and 111 Democrats.