There have been many posters speculating on WHY Ziglar is quitting. My personal opinion is that he was TOLD to resign. I know there are many on this thread who won't give Bush credit for anything, but this situation has all the hallmarks of a typical DC firing.
"I want to pursue opportunities in the private sector"
"I've spent many years in government service and I want to spend time with my family".
Many other statements like the above are used as typical diplo-speak to cover a canning.
In any case: GO MICHELLE, we need you at INS