NEW : Leaks go `` to the heart of our efforts to combat terrorism , '' W.H . spokesman says . NEW : Obama believes the programs balance security , privacy issues . Comment: Democratic Rep. Conyers and others challenge the covert programs .
NEW : Leaks go `` to the heart of our efforts to combat terrorism , '' W.H . spokesman says . NEW : Obama believes the programs balance security , privacy issues . FBI director says surveillance programs possibly could have detected a 9/11 hijacker . Democratic Rep. Conyers and others challenge the covert programs .