Obama has hired Susan Sher, a "longtime mentor and friend" from Chicago, to replace Jackie Norris.
"Since the beginning of this administration," the first lady said in a statement, "Susan has served as a senior member of the East Wing and West Wing teams providing legal counsel, working as a member of the health care reform task force and leading Jewish outreach, and her transition to chief of staff will be seamless."
According to her statement, Norris is becoming a senior advisor to the Corporation for National and Community Service.
"Jackie Norris has been a colleague and friend since the earliest days of the Iowa campaign," Obama said. "She has built a strong organization in the East Wing and made tremendous progress on issues that are important to me and the president."