The revelations reignited the debate about the NSA eavesdropping program and caused new problems for Air Force Gen. Michael Hayden, the agency's former director who's now Bush's nominee to run the CIA. Hayden's role in developing and defending the secret surveillance program had been a sore spot with many lawmakers even before the latest disclosures.

"Enough is enough," said Sen. John Kerry, D-Mass., calling for the Senate to reject Hayden.

Sen. Dianne Feinstein, D-Calif., a member of the Senate Intelligence Committee and a supporter of Hayden, said the new revelation could imperil Hayden's confirmation because "this program is of substantial concern to members, no question."

Hayden sought to tamp down opposition in private meetings with lawmakers Thursday. He declined to discuss NSA data collection.

"All I would want to say is that everything that NSA does is very carefully done, and that appropriate members of the Congress — House and Senate — are briefed on all NSA activities," he said between meetings.

Senate Intelligence Committee Chairman Pat Roberts, R-Kan., said the program "is lawful and absolutely necessary" and said members of his committee have been properly briefed about it.

"Calls for further oversight are unnecessary," Roberts said.

Sen. Trent Lott, R-Miss., a member of the intelligence committee who's been briefed about the secret NSA program, said Specter should back off.

"Do we want security . . . or do we want to get in a twit about our civil libertarian rights?" he said.