Supporters and critics of the National Security Agency are preparing for a showdown on Capitol Hill over how to reform the agency in the wake of the leaks by Edward Snowden. 

Defenders of the agency — primarily the leaders of the House and Senate Intelligence committees — are preparing legislation that would increase transparency but mostly preserve the government’s sweeping surveillance powers.

{mosads} But other lawmakers, including Senate Judiciary Committee Chairman Patrick Leahy (D-Vt.), are working on legislation to dramatically rein in the NSA and end the controversial bulk collection of Americans’ phone records.

It’s too soon to tell which approach will win out.

In the Senate, the Intelligence panel is expected to vote on legislation on Thursday that would actually expand the NSA’s powers in one important way. 

The bill, which is being written by Intelligence Committee Chairwoman Dianne Feinstein (D-Calif.), would allow the agency to continue spying on a foreign national without a warrant for seven days after he or she enters the United States.

The markup of the bill will be closed to the press.

 The legislation would tweak — but not end — the NSA’s program to collect records on all U.S. phone calls.

Feinstein said the bill would limit access to the agency’s vast database of phone records, expressly prohibit analysts from listening in on calls under the program (which they already say they don’t do) and codify the existing requirement that analysts have a “reasonable articulable suspicion” that a phone number is associated with terrorism before searching the database.

The Foreign Intelligence Surveillance Court would be able to review the agency’s decision to access a phone number’s call history after the fact.  

The Feinstein bill would also require that the Senate confirm the NSA director and would instruct the agency to produce annual reports containing statistics on its surveillance activities.

NSA Director Gen. Keith Alexander and other top intelligence officials have broadly indicated support for many of Feinstein’s proposals.

At a hearing last week, Feinstein acknowledged that certain changes are needed to restore the public’s trust in the NSA, but she insisted the programs are critical for protecting national security. 

She warned that a terror attack similar to the massacre at a mall in Nairobi, Kenya, could happen in the United States if Congress goes too far in hamstringing the NSA. 

 Sen. Saxby Chambliss (R-Ga.), the committee’s ranking member, is drafting the legislation along with Feinstein and said his goal is to maintain the NSA’s “operational effectiveness” while “recognizing privacy concerns.”

Privacy advocates haven’t seen a copy of Feinstein’s bill yet, but they are skeptical that it will address their concerns about the NSA’s ability to peer into people’s private lives with little oversight. 

Greg Nojeim, a senior counsel for the Center for Democracy and Technology, worried that the bill would put Congress on the record as supporting the NSA’s programs. 

“If the Feinstein legislation codifies bulk collection — as appears her intent — it is a step back for civil liberties, not a step forward,” he said. He warned that lawsuits by civil liberties groups challenging the bulk collection would likely be thrown out if Feinstein’s bill becomes law. 

 At the Senate Judiciary Committee, Leahy is taking a very different approach to the issue.

In a speech last week, he called for an end to the bulk collection program, saying the government has failed to show that it “is an effective counterterrorism tool, especially in light of the intrusion on Americans’ privacy rights.”

“I am convinced that the system set up in the 1970s to regulate the surveillance capabilities of our intelligence community is no longer working,” Leahy said. “We have to recalibrate.”

A coalition of privacy-focused senators — Ron Wyden (D-Ore.), Mark Udall (D-Colo.), Richard Blumenthal (D-Conn.) and Rand Paul (R-Ky.) — have also introduced a bill that would curtail the NSA’s power and tighten oversight.

Michelle Richardson, a lobbyist for the ACLU, said she believes Feinstein and Chambliss are trying to move their bill quickly to “beat the reformers to the punch.”

“They want to make sure moderate members and pro-spying offices have something they can get behind as cover with their constituents and with the press,” Richardson said. 

Competing camps are also emerging in the House over how to deal with the NSA. 

House Intelligence Committee Chairman Mike Rogers (R-Mich.), a fierce defender of the NSA, said last week that he is working on a legislative package of between eight and 15 changes to “rebuild confidence” in the agency. He didn’t discuss his proposals, but like Feinstein, he has repeatedly said he believes the NSA’s activities are critical for thwarting terrorist attacks. 

House Judiciary Committee Chairman Bob Goodlatte (R-Va.) has said “additional protections” are needed, but he has yet to outline plans for legislation.

Privacy advocates in the House are led by Reps. Justin Amash (R-Mich.) and John Conyers Jr. (D-Mich.), who have introduced legislation to end the NSA’s phone data program and toughen privacy safeguards. An amendment from Amash and Conyers to defund the NSA phone program fell seven votes short of passing in July, indicating broad support in the House for substantial privacy changes. 

Even Rep. James Sensenbrenner Jr. (R-Wis.), the original author of the Patriot Act, is working on legislation to curb the NSA’s power. 

“Congress is coming to terms with the fact that they have to address this issue,” Richardson said. “I think until pretty recently they were in denial.”