President Obama's motorcade arrives in heavy fog at Andrews Air Force Base in suburban Washington on Monday, Dec. 10, 2012, before Mr. Obama departed for Michigan. (AP Photo/Ann Heisenfelt)

Photo by: Ann Heisenfelt

President Obama's motorcade arrives in heavy fog at Andrews Air Force Base in suburban Washington on Monday, Dec. 10, 2012, before Mr. Obama departed for Michigan. (AP Photo/Ann Heisenfelt)