Key elements of the post-Sept. 11 law are set to expire next year and "some politicians in Washington act as if the threat to America will also expire on that schedule," Mr. Bush said Saturday in his weekly radio address.
"To abandon the Patriot Act would deprive law enforcement and intelligence officers of needed tools in the war on terror, and demonstrate willful blindness to a continuing threat."
Several conservative Republicans have joined liberal Democrats in saying that portions of the law are too intrusive on Americans' lives. They are threatening to allow the provisions to die at the end of next year.
Some want to impose more judicial oversight of how police and prosecutors conduct investigations.
"Our government's first duty is to protect the American people" and the Patriot Act "fulfills that duty in a way that is fully consistent with constitutional protections," Mr. Bush said.
Asked Friday whether Mr. Bush was making a campaign issue of the Patriot Act, White House spokesman Scott McClellan said the president is "going to continue to talk about it" and there are "some clear choices on this issue ... in this election."
Mr. Bush's remarks strike a theme that he will return to next week, beginning Monday in Pennsylvania, a state that is key to his re-election hopes.
There, he and law-enforcement officers will stress the Patriot Act's importance. On Tuesday, the president will speak about the Patriot Act again with law-enforcement officers in Buffalo, N.Y., the site of recent criminal cases against the Lackawanna Six, a group of Yemeni-Americans convicted of supporting terrorism by briefly attending al Qaeda camps in Afghanistan.
"Since I signed the Patriot Act into law, federal investigators have disrupted terror cells in at least six American cities," said Mr. Bush. He said that since Sept. 11, the Justice Department has charged over 300 people in terrorism-related investigations, more than half of whom have been convicted or pled guilty.
A recent study concluded that while the Justice Department has sharply increased prosecution of terrorism-related cases since the Sept. 11 attacks, many fizzled and few produced significant prison time.
Mr. Bush says the Patriot Act must not be weakened.
The law "tore down the artificial wall between the FBI and CIA, and enhanced their ability to share the information needed to hunt terrorists," said the president.
He said the Patriot Act also marked a major shift in law enforcement priorities in which "we are no longer emphasizing only the investigation of past crimes, but also the prevention of future attacks."
Because of the law, FBI agents can better conduct electronic surveillance and wiretaps on suspected terrorists, he said.