McKinney described the Act as un-American, asking "what then is the targeting by government officials of our reading material, our medical records, our bank records, our e-mails, phone calls, even the keystrokes on our computer keyboards?"
More than a dozen provisions of the Patriot Act are set to expire Dec. 31.
President Bush called on Congress again this week to make permanent the expiring provisions of the Act, just days after the London bombings last week.
Three trains and a bus were bombed in London last week.
The terror attacks killed at least 52 people.
"The terrorist threats against us will not expire at the end of this year, and neither should the protections of the Patriot Act," Bush said in a speech at the Federal Bureau of Investigation's training academy in Quantico, Va. Monday.
The Act is assailed by critics - liberals and conservatives -- as an attack on civil liberties.
The so-called "library provision" permits secret warrants for "books, records, papers, documents and other items" from businesses, hospitals and other organizations.
Critics say the government could use it to subpoena library and bookstore records, and snoop into the reading habits of innocent Americans.
"In the name of fighting the war on terror, we have been told that to be more secure means to have fewer rights," McKinney said. "We're all too busy just trying to survive to pay attention to what they're doing to us.
"But we must," she continued. "The America being built in Washington today truly will be 'un-American' if we fail to stop them."