WASHINGTON -- Homeland Security Secretary Tom Ridge, who introduced the nation to color-coded terrorist alerts and oversaw the largest government reorganization since World War II, has become the seventh member of President Bush's Cabinet to announce his resignation.

Tom Ridge Related coverage Ridge's life at a crossroads

Insisting that the nation is safer than after the Sept. 11, 2001, attacks, the former Pennsylvania governor said that he'll leave Feb. 1 unless the Senate can confirm his successor before then.

After 22 years in public service, Ridge said, he wanted to spend more time with his family and think about what to do next.

He told reporters that he now will be able to see his son Tommy play rugby and that he missed coaching his daughter Lesley's soccer team, which he did while governor. He said he intends to stay in the Washington area while his son finishes high school.

Ridge has told some friends that he has been worried about not being able to save enough for his children's college educations on his salary while living in Washington. Cabinet secretaries earn $175,700 a year.

Ridge staunchly defended his controversial red, orange, yellow and green alert system as an improvement over simply warning Americans that another attack might be imminent. He has presided over six nationwide "orange" alerts but noted that there had been none since last Christmas. The nation has never gone to "red," the most severe alert. It now is under a "yellow" alert.

Ridge, 59, who was in his second term as governor when Bush asked him to become his homeland security adviser in October 2001, became the first secretary of the new Department of Homeland Security in early 2003. In that role, he has overseen the merger of 180,000 employees from other government agencies, including the Immigration and Naturalization Service and the Customs Service. The new Transportation Security Administration, which is responsible for beefed-up security at the nation's airports, also has been under his direction.

Repeating what he said many times before, Ridge yesterday said federal security employees must make "a billion-plus" correct decisions a year, while a terrorist must be right only once. Ridge has warned that another attack could come during the holidays or timed to Bush's re-inauguration Jan. 20.

"I think we've accomplished a great deal in a short period of time," he said. "As I said to the president, there will always be more work for us to do in homeland security. But if you take a look at many of the innovations, the improvements to security, the enhancements to safety at ports of entry, the partnerships that we've developed with the state and locals and the private sector, just all in all I think it's a reflection of the commitment and the dedication and the energy and the professionalism -- really, the combined power of about 180,000 people strong."

One of Ridge's proudest achievements was forging a relationship linking national, state and local homeland security officials. But he has faced criticism for not doing more to secure the borders, make ports safer and for not overseeing all national intelligence, as the legislation creating his department directed him to do.

The House is expected to meet next week to consider a Senate-passed bill supported by the bipartisan 9/11 Commission that would create a new post of national intelligence director. It is opposed by several key Republicans.

University of Maryland law professor Michael Greenberger, who directs the university's Center for Health and Homeland Security, yesterday said Ridge deserved to be saluted for reassuring Americans worried about terrorism and may even get credit for helping reelect Bush. But his failure to coordinate intelligence, Greenberger said, "was a major administrative shortcoming." He also said not enough has been done to tighten the nation's southwestern border, improve port security or help "woefully understaffed and underfunded" police and fire departments.

James Carafano, a senior fellow at The Heritage Foundation, a conservative think tank in Washington, said Ridge's greatest contribution had been to forge a homeland security strategy based on a "layered defense" of many entities "working together to prevent, respond to and recover from terrorist attacks." He praised programs that Ridge oversaw, including US VISIT, an automated entry-exit system to track visitors entering and leaving the country; a container security initiative that works with foreign ports to identify high-risk cargo; and a national incident management system that aims to standardize procedures for emergency responders.

But Carafano said Ridge's successor must improve the department's management by consolidating agencies in border and transportation security, clarifying who is in control for biodefense and cyberdefense and improving the way resources are allocated and money is spent.

Sen. Susan Collins, R-Maine, who chairs the Senate Homeland Security and Government Affairs Committee, said Ridge should be commended for working to increase cooperation among various levels of government, improving communication with first responders and creating the largest department in five decades.

White House sources said Bush, who was in Canada yesterday, has not yet made a decision about who will replace Ridge. Speculation has centered on Fran Townsend, who succeeded Ridge as the White House homeland security adviser; former Arkansas Rep. Asa Hutchinson, who is now responsible for border and transportation security under Ridge; former Virginia Gov. James Gilmore, who chaired an independent commission on intelligence; Massachusetts Gov. Mitt Romney; and former New York Mayor Rudy Giuliani.

Ridge said he found his job no more exhausting than those of the thousands of Homeland Security employees around the nation and said he had no disappointments. "I like going to work every day; there are certain days I just enjoy it even more," he said. "I guess there ... are no disappointments. There are certain things I wish we could have probably accomplished a little bit earlier."

One of those, he said, was working with the European Union more aggressively a year sooner.

Ridge faced ridicule after holding a news conference to advocate that U.S. households not only have a safety and communication plan ready for the prospect of a biological, radiological or chemical attack but also buy plastic sheeting and duct tape to seal off their basements in the event of an attack. But he maintained that Americans must get used to planning for emergencies, much as they did during the Cold War, when the concern was over a potential nuclear war.

The six other members of Bush's Cabinet have announced that they are leaving. They are Attorney General John Ashcroft, Secretary of State Colin Powell, Education Secretary Rod Paige, Energy Secretary Spencer Abraham, Commerce Secretary Donald Evans and Agriculture Secretary Ann Veneman.