President Obama greets the crowd after arriving for a campaign stop at Loudoun County High School on Thursday, Aug. 2, 2012, in Leesburg, Va. (AP Photo/Evan Vucci)

Photo by: Evan Vucci

President Obama greets the crowd after arriving for a campaign stop at Loudoun County High School on Thursday, Aug. 2, 2012, in Leesburg, Va. (AP Photo/Evan Vucci)