President Obama will tomorrow name current Chief of Staff Jack Lew as his nominee for Treasury secretary, a source tells Bloomberg News. Obama has already offered the position to Lew, the source says. The move doesn't exactly come as a surprise; Lew, a former director of the Office of Management and Budget, has long been rumored to be Obama's top choice to replace Tim Geithner, who intends to depart at the end of January. (More Jack Lew stories.)