Republicans struggled Thursday to keep a permanent extension of the Patriot Act on track as critics appeared to gain ground in their bid to derail the anti-terrorism legislation.

The two sides were poised for battle on the Senate floor today, where a filibuster was planned to force the framers of a House-backed compromise bill back to the drawing board.

The opponents gained momentum when Sen. Dianne Feinstein (D-Calif.), a defender of the original Patriot Act, said she would support a filibuster. The White House and the Republican leadership sought to corral votes to avoid a year-end political embarrassment.

A deeply divided chamber engaged in an often-emotional debate Thursday, weighing issues of security and liberty on a day that one member noted was the anniversary of the ratification in 1791 of what would become known as the Bill of Rights, including the 4th Amendment’s right against unreasonable searches.


“It is ironic ... that we are considering legislation that would greatly undermine that principle, " said Sen. Ken Salazar (D-Colo.), part of a bipartisan group of nine senators building support for the filibuster.

Senate Majority Leader Bill Frist (R-Tenn.), while acknowledging that the vote would be close, said Thursday he expected the Senate to overcome opposition and pass the legislation. “We’ll have the votes by tomorrow,” Frist said.

But Sen. Patrick J. Leahy (D-Vt.), a leading opponent of the measure, dismissed the prediction and said opponents appeared to have enough support to sustain the procedural stalling tactic.

Sixty votes would be needed in the 100-member chamber to end debate and move to passage of the legislation. The arithmetic could pose a problem: Republicans hold 55 seats, but four are committed to opposing the legislation; even absent further defections, supporters would have to win over nine Democrats.


Senate Republicans were developing a backup plan in case the filibuster threat succeeded, such as a short-term extension of the law in its original form. Others speculated that the leadership might pull the bill at the last minute to avoid an embarrassing denouement.

Feinstein, a moderate who has been a defender of the current law, is considered an important swing vote in the debate. She and others predicted the act would be extended in some form, but without agreement on key changes.

“What will be lost is the much-needed sense that the Patriot Act represents a broad consensus,” Feinstein said on the Senate floor. “Having a consensus bill is of paramount importance.”

The uncertain fate of the legislation owes much to an unlikely alliance that includes Wisconsin Sen. Russell D. Feingold, a possible 2008 Democratic presidential candidate, and several conservative Republicans. The group said the White House miscalculated by not taking their concerns more seriously.


“I think the president has not been especially well-served by those who took on the responsibility of crafting this extension,” said New Hampshire Sen. John E. Sununu, one of four Republicans who support the filibuster.

“I think the administration has been surprised about the depth and breadth of concern on this issue,” Sununu said in an interview. “It is another indication of their lack of engagement. They shouldn’t be surprised. They thought it would be an easy vote.... We all know it is going to be very close.”

The sticking points involve what Sununu described as “a few areas of a very large bill.” Sixteen provisions of the Patriot Act expire on Dec. 31, although the debate has zeroed in on a few, including one popularly known as “the library provision.”

In general, critics contend the law should be changed to require federal agents, when requesting records in terrorism cases, to demonstrate a closer connection between the records they are seeking and terrorism suspects. Without that connection, they say, authorities can engage in fishing expeditions that intrude on the lives of ordinary citizens.


At the same time, many of the provisions have been little-used. The Justice Department has estimated that a form of search warrant that has been at the center of the debate constitutes less than 1% of the number of federal search warrants executed since the attacks of Sept. 11, 2001.

Another section that gives the government authority to obtain records from a broad array of businesses, including libraries and bookstores, has been used a few dozen times, Justice has said.

Supporters predicted dire consequences if the bill did not pass. The Patriot Act “will prevent future acts of terrorism unless we allow it to expire,” Sen. Jon Kyl (R-Ariz.) said. If a filibuster resulted in the act’s ceasing to exist and an attack occurred, “everyone who votes to support a filibuster will have to answer for that,” Kyl said.

Opponents denied they wanted to kill the law. They said they wanted to improve it.


“Jon, you’re wrong,” said Sen. Larry E. Craig, an Idaho Republican. “Jon, you’re just flat wrong. We are talking about and focusing on a very small part.”