Rebuffed by both chambers of Congress, the chairman of the Senate Intelligence Committee on Thursday launched a new effort to expand the FBI's subpoena power in terrorism cases.

As House and Senate negotiators opened talks on the expiring USA Patriot Act, Sen. Pat Roberts, R-Kan., said talks have moved toward withholding some of the tools law enforcement agencies need to fight a war on terror.

He said he will push hard for the panel to enact administrative subpoena power in the final product. In June, his panel included the expanded power to subpoena records without the approval of a judge or grand jury in terrorism investigations. But the Senate and the House passed their bills without the provision, long sought by the Bush administration.

"Why is it that on our number one security threat, we balk?" Roberts asked the panel of 32 lawmakers, which includes himself.

Other committee members said caution makes sense when Congress is considering expanding the government's power to monitor the most private areas of people's lives. They pointed to recent reports that some 30,000 national security letters (NSL) — issued by FBI agents without approval of a judge or grand jury — are secretly issued every year, a 100-fold increase over their use historically.

"You can't open up the paper or turn on the TV without hearing (about) public concern about the Patriot Act," said Senate Judiciary Committee Chairman Arlen Specter, R-Pa.

Five senators of both parties sent letters Thursday to Attorney General Alberto R. Gonzales and Justice Department Inspector General Glenn A. Fine asking for a review of NSLs and to declassify the number issued every year. The letters were signed by Democrats Dick Durbin of Illinois, Russ Feingold of Wisconsin and Ken Salazar of Colorado and Republicans Larry Craig of Idaho and John Sununu of New Hampshire.

The Justice Department rejected a similar request from Durbin last summer. In his response, Assistant Attorney General William E. Moschella called any such disclosure inappropriate "at this time in light of the national security interests in question."

Congress passed the Patriot Act shortly after the Sept. 11 terrorist attacks to give federal law enforcement officers and intelligence agencies more muscle in the fight against terror. Fourteen provisions of the act expire on Dec. 31 unless renewed by Congress and signed into law by the president.