Two U.S. Senators are proposing changes to a sweeping anti-terrorism law.  The legislation would affect controversial provisions that are set to expire at the end of the year, and which top Bush administration officials are urging Congress to renew. 

The Patriot Act was passed by Congress shortly after the September 11, 2001, terrorist attacks on the United States.  It gave the government greater powers to conduct clandestine searches and surveillance in a range of criminal cases.

Attorney General Alberto Gonzales told the Senate Judiciary Committee Tuesday the law has been successful in preventing further attacks on U.S. soil, and called on Congress to renew those provisions set to expire by year's end.

"The act has a proven record of success in protecting the security of the American people, and we cannot afford to allow its most important provisions to sunset," said Mr. Gonzales.

FBI Director Robert Mueller echoed the comments.

But critics say the law's more controversial provisions undermine civil liberties.  They cite provisions allowing the FBI to obtain records in terrorism-related cases from businesses and other entities, including libraries, and allowing so-called sneak-and-peek searches without telling suspects their homes or businesses had been searched.

Senator Larry Craig, an Idaho Republican, is introducing legislation to amend the provisions.  Senator Dick Durbin, an Illinois Democrat, is a cosponsor:

"If there is any wisdom in this Patriot Act, which I voted for, it was the sunset provisions, which said we will revisit these things, we will determine whether or not we were caught up in the emotion of the moment and have gone too far," said Mr. Durbin.

The bill would, among other things, impose some limits on the government's powers to search Americans' homes or businesses without notifying them for weeks or months.  It would also require the FBI to have probable cause in gaining access to Americans' medical, business, or library records.

Similar legislation is expected to be introduced in the House of Representatives.

For his part, Attorney General Gonzales signaled his willingness to consider changes to the law, as long as they do not weaken efforts to fight terrorism.

"As Congress considers whether to renew these provisions, I am open to suggestions for clarifying and strengthening the act," he added.

The Senate Judiciary Committee hearing is the first in a series of congressional hearings in the coming months on whether to renew the provisions of the Patriot Act.