President Barack Obama walks along the tarmac with California Attorney General Kamala Harris, center and Lt. Gov. Gavin Newsom, left, after Obama arrived on Air Force One, Thursday, Feb. 17, 2011, in San Francisco, at San Francisco International Airport.  (AP Photo/Carolyn Kaster)

Photo by: Carolyn Kaster

President Barack Obama walks along the tarmac with California Attorney General Kamala Harris, center and Lt. Gov. Gavin Newsom, left, after Obama arrived on Air Force One, Thursday, Feb. 17, 2011, in San Francisco, at San Francisco International Airport. (AP Photo/Carolyn Kaster)