Updated

One of the few points of agreement during the Sept. 11 commission hearings has been that elements of the Patriot Act (search) are key to fighting terrorism. That's part of the reason President Bush is pushing for renewing the act, set to expire at the end of next year.

Bush headed to the electorally-important state of Pennsylvania on Monday, where he told a gathering of town supervisors that the Patriot Act is protecting America from terrorists.

"The next time you hear somebody attacking the Patriot Act, the Patriot Act defends our liberty. The Patriot Act makes it able for those of us in positions of responsibility to defend the liberty of the American people. It's an essential law," he said.

Clinton and Bush administration officials have acknowledged that the so-called "wall" that was up between criminal law enforcement and international intelligence agencies prior to Sept. 11 kept information from being shared between critical crime-fighting units. The Patriot Act, the president argued, has knocked down those walls.

"You hear the talk about the walls that separated certain aspects of government. They have been removed by the Patriot Act, and now law enforcement and intelligence communities are working together to share information to better prevent an attack on America," he said.

Bush said since the act was enacted into law shortly after the Sept. 11, 2001, terror attacks, authorities have started working together in a way they could not earlier. The law, he said, is in part responsible for the ability to break up seven terrorists cells inside the United States (search) — from New York to Oregon.

Critics of the act warn, however, that the government's expanded use of wiretaps, its surveillance and detention powers has seriously set back civil liberties that were once held in the highest regard in the United States, but have now been sacrificed to national security.

"Bush clearly is fighting a defensive battle against both Democrats and Republicans who are asking questions about the Patriot Act," said Anthony Romero, executive director of the American Civil Liberties Union (search). "Increasingly, there are hard questions coming from Democrats and Republicans about whether we went too far too fast."

The Patriot Act passed Congress with wide margins, but liberal and conservative members both have threatened to let some of the act's provisions die at the end of 2005, when about 10 percent of the act is set to expire.

Independently, state and local lawmakers have passed resolutions in Alaska, Hawaii, Vermont, Maine and elsewhere ordering community law enforcement to ignore portions of the act. The ACLU says more than 291 communities representing nearly 50 million people in 39 states have supported resolutions critical of the law.

Bush, who addressed two separate events on Monday, will speak again about the act in Buffalo, N.Y., on Tuesday. He also discussed the legislation in his weekly radio address on Saturday. In that address, Bush said that allowing parts of the Patriot Act to expire next year would demonstrate a "willful blindness to a continuing threat."

On Monday, Bush said the practices allowed in the act have long been used to investigate drug cartels and organized crime families, and explained that the permission to seek a wiretap on a person rather than on a telephone is needed because the introduction of technology has made it easy for criminals to toss cell phones and get new ones, leading law enforcement on a paper chase for subpoenas rather than on a pursuit of criminals.

The CATO Institute's (search) director of the Project on Criminal Justice told Fox News that that authority is dangerous.

"Now the agents basically have their own search warrants in their own pockets. They call them national security letters this is something that I think endangers all of our rights and our privacy," said Director Tim Lynch.

Asked whether Bush is using the act for election purposes, White House spokesman Scott McClellan said the president will continue to talk about issues that present "clear choices" for voters in November.

While on the road on Monday, Bush was also attending a fund-raiser for Sen. Arlen Specter, the four-term moderate facing a tough challenge from conservative Rep. Pat Toomey. The GOP primary is scheduled for next Tuesday.

Specter is considered an asset to keeping the Senate in Republican hands in a state that gave Al Gore the presidential nod in 2000 by 50.6 percent to 46.4 percent. The state has 21 electoral votes. But Specter's stance on the Patriot Act puts him at odds with the administration. He is one of 18 co-sponsors of legislation, introduced by Sen. Larry Craig, R-Idaho, that would amend the law.

Fox News' Jim Angle and Caroline Shively and The Associated Press contributed to this report.