Christina Romer, chair of the White House Council of Economic Advisers has resigned. She is the second member this summer to leave the president's economic team. Romer, an expert on the Great Depression, was instrumental in crafting the $862 billion economic stimulus package. She will return to U.C. Berkeley, where she is an economics professor. Chrystia Freeland, global editor in chief of Reuter says that it is fairly common to see big moves when there is a midterm election on the horizon.