Washington took note when first lady Michelle Obama suddenly sacked her chief of staff in favor of her old boss from Chicago at the beginning of June. It was widely seen as a sign that the first lady wanted to start pumping up policy as well as her biceps. The new chief of staff, Susan Sher, had helped Obama move from an unsatisfying job as a corporate lawyer grinding out billable hours to a lush, $317,000-a-year community relations job at the University of Chicago Medical Center. Sher, Senior White House Adviser Valerie Jarrett and the first lady are close friends....