As Congress moves forward on President Bush's proposal to create a Cabinet-level Department of Homeland Security, the president used Monday to outline support for its "overriding and urgent" mission.

Bush said the new Cabinet agency, made up of 100 different security and safety units around the nation, will work to control movement at the borders, emphasize coordination with state and local emergency responders, merge intelligence units under one roof to identify and map threats and address vulnerabilities, and develop technologies to protect the homeland.

"We need to learn to set priorities in the government, and the number one priority is to protect Americans from attack because we're at war," Bush told workers at the Argonne National Laboratory, which develops some of the technologies being used to counter attacks.

"We will harness our science and our technology in a way that protects American people. We will consolidate most federally-funded homeland research and development to avoid duplication and to make sure all the elements are focused," Bush said.

Argonne National Laboratory is a branch of the University of Chicago, site of the first nuclear-chain reaction, and one of 15 labs run by the Energy Department, but now in sight for a move to the new homeland security department.

Argonne has created cyanide and anthrax detectors. Monday, the administration sent out new guidelines for testing for anthrax after a study showed the tests used last fall were unreliable. Argonne has also developed a computer program that detects biological or chemical attacks and tracks them by analyzing symptoms reported by hospitals and emergency medical technicians.

Argonne also developed a chip that can detect the presence of nuclear material, the star of the president's tour Monday.

Bush got a demonstration of the nuclear detection device, which is about the size of a deck of cards, supposedly simple to operate, and part of a lunchbox-sized unit that police or soldiers can take to the scene of a terrorist attack to determine whether a biological or radiological agent has been used.

Bush said that since "our scientific community is serving on the front lines of this war by developing new technologies that will make America safer," the government will do what it can to make their job easier.

Bush has urged Congress to develop a new Department of Homeland Security, which he wants created before the end of the year. He said Monday that the House speaker told him he could expect a vote this week. The president's Cabinet secretaries are calling lawmakers to generate support, but members have expressed substantial concerns against giving the president the authority to shift the agency's activities and appropriations without notice.

Bush said it is necessary to respond to any attack that might come.

"The new secretary needs the ability to move money and resources quickly to respond to true threats. We're in new times in America, and that requires new thinking. And Congress must give us the flexibility necessary to make the right decisions to achieve our goal which is to protect the American people," he said.

The potential use of the military in the wake of a terrorist attack is one of the parts of the counterterrorism strategy raising concern by some lawmakers, who are reluctant to amend the Posse Comitatus Act, a 19th century law that prevents the military from serving on the homeland.

The president is also urging congressional members to approve the move of the Secret Service, the Customs Service, the Coast Guard and the Federal Emergency Management Agency under the new homeland security umbrella. Lawmakers on several committees have opposed those changes.

Fox News' Wendell Goler contributed to this report.