Rested up from his Hawaiian vacation and facing a newly empowered GOP, President Obama is preparing a major staff overhaul. Chief economic adviser Larry Summers is headed back to Harvard in January, where he will resume teaching and academic research. Press secretary Robert Gibbs may also depart soon, as could acting chief of staff Peter Rouse. Obama is reportedly considering former JPMorgan Chase exec and U.S. Commerce Sec. William Daley for the chief of staff spot, which Rahm Emanuel left this fall and Rouse has been holding down since. Top adviser David Axelrod and deputy chief of staff Jim Messina are expected to depart soon to run Obama’s 2012 campaign.