Sen. Mark Udall (D-CO) and Ron Wyden (D-OR) have seen no evidence to justify this claim. From Wyden:
We have not yet seen any evidence showing that the NSA’s dragnet collection of Americans’ phone records has produced any uniquely valuable intelligence. Gen. Alexander’s testimony yesterday suggested that the NSA’s bulk phone records collection program helped thwart ‘dozens’ of terrorist attacks, but all of the plots that he mentioned appear to have been identified using other collection methods. The public deserves a clear explanation,” Udall and Wyden said. “We look forward to reviewing the analysis that the general has promised to provide showing how the intelligence community arrived at these numbers. In our view, a key measure of the effectiveness of the bulk collection program will be whether it provided any intelligence that couldn’t be obtained through other methods.”
I will say it again. If the only way you can defend your programs is to lie about it, then it is probably a very bad program.
This “debate” Obama has welcomed about what is the proper balance is completely based on one side being able to make bold claims they know they won’t need to prove to the public.