Though NSA supporters say the program is an effective tool against terrorism and has prevented attacks in the past, a new study by a nonpartisan think tank found that its contribution has been minimal at best, and far short of those oft-claimed 54 thwarted attacks.

The only case New America Foundation found that was initiated by NSA's bulk metadata collection program was that of Basaaly Saeed Moalin, a cab driver in San Diego who, along with three others, was convicted of sending several thousand dollars to terrorist group al-Shabaab. But there was no threat of a terrorist attack in that case, and the four men are appealing the conviction on the grounds that the NSA's surveillance violated their constitutional rights.

The study's findings, which will be released tomorrow but the Washington Post has a good summary of now, echo that of President Obama's NSA review panel, which said the phone metadata collection program was "not essential to preventing attacks" and recommended ending it.

So far, none of the panel's 46 recommendations have been implemented. Last week, the Foreign Intelligence Surveillance Court renewed the phone metadata collection program for another 90 days.