Despite facing efforts by some in his party to scale back the post-9/11 security legislation, Bush insisted it closes "dangerous gaps" in America's law enforcement and intelligence capabilities.
US politicians initially responded to the 2001 attacks by overwhelmingly approving the law 45 days later.
It allowed expanded surveillance of suspects, increased use of material witness warrants to hold suspects incommunicado and permitted secret proceedings in immigration cases.
But more than a dozen of its provisions are set to expire.
Those provisions, among other things, provide authority for nationwide search warrants, enable the FBI and intelligence agencies to share information about terrorism cases and gave the FBI the power to obtain records in terrorism-related cases from entities such as libraries.
Freedom v safety
During Bush's 2004 re-election campaign, he made preserving the law a refrain but has rarely spoken of it since.
His renewed focus came as Congress has begun working on the act's renewal amid fresh criticisms - from members of both parties - that it undermines basic freedoms.
Bush pressured Congress to make the expiring provisions permanent. His administration also is seeking greater powers for the FBI to subpoena records in terrorism investigations without the approval of a judge or grand jury.
"My message to Congress is clear: Terrorist threats against us will not expire at the end of the year and neither should the protections of the Patriot Act"
"My message to Congress is clear: Terrorist threats against us will not expire at the end of the year and neither should the protections of the Patriot Act," Bush told more than 100 law enforcement officers.
The president credited the law with helping to bring federal charges against more than 400 suspects - more than half of whom have been convicted - and to break up terror cells.
He spoke at the Ohio Patrol Training Academy to highlight the case of a Columbus, Ohio, man, Iyman Faris, who was accused of plotting attacks on a New York bridge and a Midwest shopping mall but was tracked down with the help of the Patriot Act.
Bush said Faris met Usama bin Ladin in 2000 at an al-Qaida training camp in Afghanistan.
Later, he received instructions from top terror leader Khalid Shaikh Mohammed to destroy the Brooklyn Bridge. Now, because of the Patriot Act, Bush said, Faris has provided information about al-Qaida and is serving a 20-year prison sentence.
On Tuesday, the Senate Intelligence Committee approved revisions to the law that would give the FBI the expanded administrative subpoena powers the Bush administration has been seeking.
But much of the debate in Congress has focused on possible limits to the law.
Republican Senator Larry Craig and Democratic Senator Dick Durbin want to tighten standards for the law's "sneak and peek" warrants issued without immediate notification of the target and for "roving" wiretaps, and to exempt libraries from provisions that allow FBI expanded access to records.
The administration has warned that the Craig-Durbin bill would draw a Bush veto. The president did not repeat that threat, but he singled out the roving wiretap as an "especially important" tool that has been used successfully for years against drug dealers and others.
Lisa Graves, the ACLU's senior counsel for legislative strategy, said the lack of a documented case of abuse did not mean the law does not violate civil liberties.
She said the Justice Department's inspector general reported that 7000 people have complained of abuse and countless others do not even know they have been subjected to a search because the law requires that they be kept secret.
The ACLU wants the government to show evidence of a connection to terrorist activity before being allowed to search records.