A bipartisan group of senators is standing firm in its opposition to the renewal of controversial anti-terrorism laws because of concerns about the infringement of civil liberties. Key provisions of the law, known as the Patriot Act, are set to expire in just over a week. Senators are trying to find a compromise on the legislation, which is strongly backed by the White House.

The group of senators who blocked the bill renewing the Patriot Act from coming to a vote last week do not want provisions of the law to expire, as they are set to do on December 31.

Instead, the senators - mostly minority Democrats, but some majority Republicans - want to extend the current law by three months to allow lawmakers to strengthen civil liberties' protections in the legislation.

They released a letter sent to Majority Leader Bill Frist signed by 52 senators who support such an extension in the 100-member senate.

Senator Patrick Leahy, a Vermont Democrat, is leading the effort.

"What we are trying to do is achieve a balanced and effective Patriot Act, one that promotes our security and preserves our freedom," he said.

Senator John Sununu, a New Hampshire Republican, is also behind the effort.

"There is no reason why we need to leave here without keeping elements of the Patriot Act in place," he said.

But Majority Leader Frist dismissed the idea, saying the proposed legislation to renew the Patriot Act is an improvement over the current law.

"It is a better bill," he said. "Everybody agrees that the current bill that is on the floor is a better bill."

President Bush also opposes any extension of the current law, and repeated his call on the Senate to end delays and renew the Patriot Act.

"This obstruction is inexcusable," he said. "The Senators obstructing the Patriot Act need to understand that the expiration of this vital law will endanger America and will leave us in a weaker position in the fight against brutal killers."

At issue are provisions up for renewal that include those dealing with wiretapping and access to library and business records that critics say give too much power to the government.

Attorney General Alberto Gonzales argues otherwise. He says there are civil liberties' protections in the legislation, and any changes to the bill could hamper law enforcement efforts.