By Kevin Anderson
BBC News, Washington
There was nothing surprising in the resignation of Tom Ridge, secretary of the recently formed US Department of Homeland Security.
The move had been long rumoured as part of the routine round of cabinet resignations that follow the re-election of a president.
Ridge: Exhausted by office or seeking the presidency?
Mr Ridge oversaw the largest re-organisation in the US government since World War II and can point to a number of accomplishments including merging US border security efforts.
But he leaves office with more things to do than he was able to get done in his short tenure.
As he formally announced his resignation, he sounded much like the man ready to cast off the weight of a high-stress, high-profile public position.
After more than 22 years of public service, he said that he "wanted to step back and pay a little more attention to personal matters" including his son's rugby games.
He not only had to meld the mechanics but also the cultures of agencies which previously existed elsewhere in the Leviathan that is the US government
Asked about his plans, he said that he wanted to take a break before deciding on his future.
Some in Washington have said he is simply exhausted and wants to enter the private sector to earn more money as his children enter university. Others say he has presidential ambitions.
Mr Ridge has a right to be exhausted after 20 months of merging 22 agencies including the Coast Guard, Secret Service, Customs Service and the Immigration and Naturalisation Service into the Department of Homeland Security (DHS).
He not only had to meld the mechanics of these agencies - the business, accounting, personnel and information systems - but also the cultures of agencies which previously existed elsewhere in the Leviathan that is the US government.
The newly formed agency has some 180,000 employees.
"It was a massive merger-and-acquisition, and it was not the normal timeline to allow for due diligence to make sure all the parts fit together," said David Heyman, the director of the Homeland Security Programme at the Centre for Strategic and International Studies.
Mr Ridge can point to several accomplishments including integration of US border security efforts, Mr Heyman said, but much remains to be done.
The integration did not always go smoothly. There were bumps in the road and more bumps to come, Mr Heyman said.
And the department and Mr Ridge had their critics. He created the much-maligned colour-coded terrorist threat-level system.
He was criticised by some for needlessly frightening citizens by raising the threat level based on vague information.
But as he left, he said that he always erred on the side of divulging more information and hoped that his successor would follow his lead.
President Bush was on a state visit to Canada when Secretary Ridge announced his resignation, and no successor was immediately announced.
Mr Ridge said that he would stay on until 1 February unless a successor was named earlier.
But a long list of names were circulating in Washington as possible successors:
Several former and current state governors
Federal Emergency Management Agency director Joe Allbaugh
DHS deputy Admiral James Loy
DHS undersecretary for transportation and border security Asa Hutchinson
White House Homeland Security advisor Frances Fragos Townsend.
Mr Heyman believes that bringing someone in from the outside of the new organisation might be disruptive and suggested that Asa Hutchinson most likely has the inside track.
Not only could he provide a seamless transition but also, as a former member of Congress, he has the political skills to be the public face of the department.
But whoever takes over the job, Mr Ridge leaves much left to do at a post he took over and created only 20 months ago.
"If you look back at his tenure, he was a crisis manager. He had to plug holes in United States' greatest vulnerabilities," Mr Heyman said.
The US has much to do to protect chemical facilities and its cargo, train and transport network, Mr Heyman said, and Mr Ridge was barely able to address the international issues related to US domestic security.
And apart from creating the post, Mr Ridge's most notable accomplishment was to set the standard for successors.
"There were no attacks during his watch and that is the bar that he has been set," Mr Heyman said.