President Barack Obama will Friday announce plans to stop the National Security Agency hoarding hundreds of millions of telephone call records, among reforms to US surveillance programs exposed by Edward Snowden.
A senior US official, speaking ahead of Obama's speech on NSA programs, said that Obama believed trawling for telephone "metadata" was vital to fighting terrorism, but needed to be reformed to preserve civil liberties.
"In his speech, the president will say that he is ordering a transition that will end the Section 215 telephone metadata program as it currently exists," the senior official told AFP.
The president foresees a move to a program "that preserves the capabilities we need without the government holding this bulk metadata."
"The president believes that the 215 program addresses important capabilities that allow us to counter terrorism, but that we can and should be able to preserve those capabilities while addressing the privacy and civil liberties concerns that are raised by the government holding this metadata."
It was not immediately clear how Obama would accomplish the reform or whether he would leave it up to Congress to decide which entity should hold the call data.
Telecommunications companies have balked at suggestions that data on the destination and duration of calls should be held within their servers and be accessed by US spies armed with court permission.
Some activists have suggested a third party company could be charged with holding the data.
Obama will also order Friday another immediate change to the system of telephone data dragnets, requiring a judicial finding before the NSA can query the database, the official said.
Obama has also asked Attorney General Eric Holder and the intelligence community to report to him by March 28 on how the program can be preserved without the government holding the metadata.
Snowden, a fugitive US contractor now exiled in Russia, has fueled months of revelations by media organizations over data mining and spying on foreign leaders by the NSA in one of the biggest security breaches in US history.
The disclosures have infuriated US allies, embarrassed Obama administration diplomats and shocked privacy campaigners and lawmakers.
The White House has assured Americans that data on phone calls and Internet use is only collected to build patterns of contacts between terror suspects -- and that US spies are not listening in.
But Obama has said that one of his goals in Friday's speech at the US Justice Department is to restore public confidence in the clandestine community.
His appearance follows a prolonged period of soul-searching and policy reviews by the White House.
On the eve of the speech, Britain's Guardian newspaper and Channel 4 News splashed the latest revelations from Snowden.
Their reports said the NSA had collected almost 200 million mobile phone text messages a day from around the world, and used them to extract data on the location, contact networks and credit card details of mobile users.
Civil liberties activists are bracing themselves for disappointment.
Michelle Richardson, legislative counsel for the American Civil Liberties Union, said Thursday that Obama would likely neither outlaw nor significantly reform bulk collection of telephone and Internet metadata.
"We are looking to the president tomorrow to make a very bold statement about reclaiming privacy. We are looking to him to take leadership about reining in this programs," she said.
"Will our government continue to spy on everyday Americans?"
Kevin Bankston, policy director of the Open Technology Institute at the New America Foundation, warned that if Obama did not announce specific reforms, the battle would shift to Congress.
"President Obama's trajectory on these issues from reformer to supporter of these programs has been very dispiriting," Bankston said.
"If he does fail to take a stand and exercise the bold leadership that is necessary, it will become Congress's responsibility to step into the breach and we look forward to working with them to do so."
Intelligence chiefs say the programs are perfectly legal, but their opponents say they are unconstitutional.
Obama is also expected to back extra privacy protections for foreigners swept up by the programs and limits to spying on friendly world leaders.
His challenge will be to prove that data mining programs, made possible by swift advances in technology, can enhance national security while restoring public confidence that individual freedoms are safe.
During his deliberations, Obama has had to reconcile his duties as a commander-in-chief sworn to keep Americans safe and his oath to uphold the US Constitution.
Not to mention guard his political flank -- Obama knows his Republican enemies would pounce if a future terror attack could be pinned on restrictions he placed on spy agency capabilities.
The president's speech will also be closely watched for any changes to the PRISM program, which mainly sweeps up Internet data on foreigners, based on records acquired from Internet companies like Google, Yahoo and Apple.