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With provisions set to expire at the end of 2006 and in an atmosphere vastly different from the first two months after the Sept. 11, 2001, terror attacks, some senators are focusing a much more critical eye on the Patriot Act (search) and considering whether to scrap some of the rules.

On Tuesday, Attorney General Alberto Gonzales (search) and FBI Director Robert Mueller (search) said the reason times are so different is because of measures taken to secure the nation. They strongly argued in favor of renewing all provisions of the act, saying it is integral to fighting the War on Terror and "crucial to national security."

"Al Qaeda (search) and other groups remain a grave threat to our country, and now is not the time for us to relinquish our tools in that fight," Gonzales told the Senate Judiciary Committee.

Mueller said sections of the law that allow intelligence and law enforcement agencies to share information are especially important.

"Experience has taught the FBI (search) that there are no neat dividing lines that distinguish criminal, terrorist and foreign intelligence activity," Mueller said in his prepared testimony.

He also asked Congress to expand the FBI's administrative subpoena powers, which allow the bureau to obtain records without approval or a judge or grand jury.

The Patriot Act was passed in October 2001 to give law enforcement agencies expanded powers to track suspected terrorists. Opponents, mainly civil libertarians and rights groups, have argued that the law gives too much power to single out individuals while denying them their civil liberties.

"Cooler heads can now see that the Patriot Act went too far, too fast and that it must be brought back in line with the Constitution," said Gregory Nojeim, associate director of the American Civil Liberties Union's (search) Washington legislative office.

In response to opposition of the law, five states and 375 communities in 43 states have passed anti-Patriot Act resolutions, the ACLU notes.

One section of the law that Gonzales suggested might be ready for revision is that which allows federal agents, in the context of terrorism investigations, to seize items like business records, including those from libraries and bookstores. The section is called the "library provision" by its critics though it does not specifically mention tracking reading habits of Americans who frequent libraries or bookstores. The section of the law permits secret warrants for "books, records, papers, documents and other items" from businesses, hospitals and other organizations.

In a statement supporting Gonzales' testimony, the Justice Department gave an example of how the law is used. It said that if a terrorism suspect were picked up by someone using a rental car, investigators can request a court order for car rental records or other information to help identify the suspects' contacts.

Gonzales told lawmakers Tuesday the provision has been used 35 times, but never to obtain library, bookstore, medical or gun sale records, only for drivers' license, credit card, apartment lease and similar records like subscriber information on phone numbers picked up during taps and traces. He said he would support clarifying the law to make clear that the request only pertains to national security investigations and the recipient of a court order may consult with an attorney and challenge the order in court.

Also at issue are the so-called "sneak and peek" provisions of the law that allow federal agents to enter private homes secretly and search for evidence without immediately telling the resident they've been there. Before the Patriot Act was passed, those delayed-notice warrants were previously reserved for mafia activity and drug trafficking cases.

While getting the warrant means obtaining a court order and the provision is not actually expiring, Sen. Dianne Feinstein, D-Calif., asked Gonzales to determine if the delayed-notice warrant has ever been used illegally.

While he obliged, Gonzales later noted that the sneak and peak rule had enabled federal officials to track over the Internet a woman who ultimately confessed to strangling an 8-months-pregnant woman and cutting the fetus from her womb.

In an aside to the Patriot Act rules, Gonzales also fielded a question from Sen. Patrick Leahy, D-Vt., ranking member of the committee, who asked whether the United States is ignoring the record on torture in some countries and sending our detainees there even when they are known to conduct beatings and electric shock.

"I think a country that would have that kind of record, we would have to receive some very special assurances to satisfy ourselves in meeting our legal obligations that it's more likely than not that someone that we sent over in their custody would not be tortured," Gonzales responded.

While Gonzales defended the Patriot Act, saying it has helped secure more than 200 guilty pleas or convictions in terror-related crimes, two lawmakers, Sens. Larry Craig, R-Idaho, and Dick Durbin, D-Ill., were reintroducing legislation designed to curb some of the provisions discussed during the hearing.

"If the goal here was, as you say, to enhance federal government sharing of intelligence, we could have stayed away from the Patriot Act altogether and really focused on the agencies' working with one another and sharing information so that ... the CIA and all the other agencies would communicate," Durbin told Gonzales.

FOX News' Megyn Kendall and Sharon Kehnemui Liss and The Associated Press contributed to this report.