President Barack Obama walks up the steps of Air Force One at Andrews Air Force Base in Md., Thursday, July 15, 2010, on his way to participate in the groundbreaking ceremony of an advanced battery plant in Michigan. (AP Photo/Susan Walsh)

Photo by: Susan Walsh

President Barack Obama walks up the steps of Air Force One at Andrews Air Force Base in Md., Thursday, July 15, 2010, on his way to participate in the groundbreaking ceremony of an advanced battery plant in Michigan. (AP Photo/Susan Walsh)