Washington (CNN) -- A top-secret program that collects phone records of Americans is legal, conducted properly and possibly could have helped detect a 9/11 hijacker had it been in place before the 2001 terrorist attacks, FBI Director Robert Mueller said Thursday. Mueller's remarks at a House Judiciary Committee hearing led an effort by Obama administration officials and some in Congress to push back against a firestorm of criticism about domestic surveillance in the aftermath of classified leaks last week that disclosed details of covert surveillance programs. Civil liberties groups and legislators on the left and right are among critics condemning the secret programs under the National Security Agency as government overreach beyond the intention and limits of the Patriot Act originally passed in the aftermath of the 9/11 terrorist attacks.
@highlight
NEW: Leaks go "to the heart of our efforts to combat terrorism," W.H. spokesman says
@highlight
NEW: Obama believes the programs balance security, privacy issues
@highlight
FBI director says surveillance programs possibly could have detected a 9/11 hijacker
@highlight
Democratic Rep. Conyers and others challenge the covert programs
The @placeholder spokesman also reiterated Obama's support for programs he says have "helped thwart dozens of attacks."