President Bush said Wednesday he wants Congress to expand and make permanent a law that temporarily gives the government more power to eavesdrop without warrants on suspected foreign terrorists.

Without such action, Bush said, "our national security professionals will lose critical tools they need to protect our country."

"It will be harder to figure out what our enemies are doing to train, recruit and infiltrate operatives into America," the president said during a visit to the super-secret National Security Agency's headquarters. "Without these tools, our country will be much more vulnerable to attack."

The Foreign Intelligence Surveillance Act governs when the government must obtain warrants for eavesdropping from a secret intelligence court. This year's update — approved just before Congress' August break — allows more efficient interceptions of foreign communications.

Under the new law, the government can eavesdrop without a court order on communications conducted by a person reasonably believed to be outside the U.S., even if an American is on one end of the conversation — so long as that American is not the intended focus or target of the surveillance.

In requesting the change, the Bush administration said technological advances in communications had created a dire gap in the ability to collect intelligence on terrorists.

Such surveillance generally was prohibited under the original law if the wiretap was conducted inside the U.S., unless a court approved it. Because of changes in technology, many more foreign communications now flow through the U.S. The new law, known as the Protect America Act, allows those to be tapped without a court order.

Civil liberties groups and many Democrats say the new changes go too far. Democratic leaders in Congress set the law to expire in six months so that it could be fine-tuned; that process now is beginning on Capitol Hill.

Democrats hope for changes that would provide additional oversight when the government eavesdrops on U.S. residents communicating with overseas parties.

Sen. Jay Rockefeller, chairman of the Senate Intelligence Committee, said lawmakers understand the need to update the law, but also the need to protect the rights and liberties of Americans.

"For over five years, the president carried out a warrantless surveillance program that ignored the law and the role of court oversight," Rockefeller said. "Today, the president continues to seek unchecked surveillance powers that many of us in Congress cannot support. The fact is, the Protect America Act did provide authority for collection, but it did not include sufficient protections for Americans. There's no reason we can't do both," Rockefeller said.

"The president needs to step up to the plate and show that he is willing to work with Congress to get this important legislation passed."

Bush timed his visit to Fort Meade to press his case.

"The threat from Al Qaeda is not going to expire in 135 days," he said, "so I call on Congress to make the Protect America Act permanent."

He also urged lawmakers to expand the law, not restrict it. One provision particularly important to the administration, but opposed by many Democrats, would grant retroactive immunity to telecommunications companies which may have helped the government conduct surveillance before January 2007 without a court order.

Bush was joined at the podium in an NSA hallway by Vice President Dick Cheney, National Intelligence Director Mike McConnell and others.

The president received private briefings from intelligence officials and mingled with employees in the National Threat Operations Center. While cameras and reporters were in the room, the large video screens that lined the walls displayed unclassified information on computer crime and signal intelligence.

Along one wall at NSA is a sign that says, "We won't back down. We never have. We never will."