Edward Snowden's revelations about widespread surveillance by the US National Security Agency (NSA) started producing real political blowback in July, with a bill that almost defunded the NSA.

Now, a group of reformist politicians is taking a more careful aim at stopping the agency's controversial practices. Senators Richard Blumenthal (D-CT), Rand Paul (R-KY), Mark Udall (D-CO), and Ron Wyden (D-OR) have introduced a bill that would stop the NSA from collecting "bulk data"—like the database it has built of every American's phone calls.

The bill, summarized here, amends two sections of the Foreign Intelligence Surveillance Act (FISA) to specifically ban bulk collection of phone and electronic communications records, such as e-mail. The government will still be able to get records of someone suspected of terrorism or espionage, but it prevents National Security Letters (NSLs) from being used for bulk data collection and requires more disclosure about how NSLs are used.

Also revised by the bill is Section 702 of FISA, preventing the government from doing warrantless searches for communications it has collected under that statute. It also creates a "constitutional advocate" who will argue against the government in the Foreign Intelligence Surveillance Court. This will rectify the fact that the court "issues its rulings in secret and almost always hears only the government's side of any case."

The Wyden-Udall-Paul bill is in competition with a bill introduced by the committee chairperson, Sen. Diane Feinstein (D-CA), that she says is more likely to gain the support of the committee. Feinstein said that “a majority of the committee” believed that the call log program was “necessary for our nation’s security," according to a New York Times report on the intelligence committee's rare public meeting.

A draft of the bill was published on Thursday—the same day that Wyden had a chance to let NSA chief General Keith Alexander know what he thought about his agency's behavior. Alexander's leadership "built an intelligence collection system that repeatedly deceived the American people," said Wyden. He continued:

Time and again, the American people were told one thing about domestic surveillance in public forums, while government agencies did something else in private. Now these secret interpretations of the law and violations of the Constitutional rights of Americans have become public; your agencies face terrible consequences that were not planned for. There has been a loss of trust in our intelligence apparatus here at home and with friendly foreign allies, and that trust is going to take time to rebuild. And in my view this loss of trust undermines America’s ability to collect intelligence on real threats, and every member of this committee knows there are very real threats out there. Your joint testimony today blames the media and others, but the fact is that this could have been avoided if the intelligence leadership had been straight with the American people and not acted like the deceptions that were practiced for years could last forever. I hope this is a lesson that your agencies are going to carry into the future.

Following that, Wyden repeatedly asked Alexander if the NSA had ever collected Americans' cell site data in bulk—which would amount to a massive gathering of location data. Alexander answered in the negative, but hedged, saying it hadn't been gathered "under Section 215." Wyden insisted that wasn't a full answer.

Alexander: As you're aware I expressly affirmed this commitment on June 25, 2013. … Additional details were also provided in the classified supplement to Director Clapper's July 25 response to this question. What I don't want to do, Senator, is put out in an unclassified forum anything that's classified here. … I saw what Director Clapper sent and I agree with it. Wyden: General, if you're responding to my question by not answering it because you think that's a classified matter, that is your right. We will continue to explore that. I believe this is something the American people have a right to know: whether NSA collected or made plans to collect cell site information.

Wyden and Udall are longtime critics of the NSA's broad view of its powers under the Patriot Act and sit on the Senate Intelligence Committee. The inclusion of Paul, a Tea Party favorite, gives the bill some support from the Republican side of the aisle.