Rep Gabrielle Giffords, Arizona Democrat, tours the Gabrielle Giffords Family Assistance Center, one of her favorite charities, with staffer Ron Barber in Tucson, Ariz., last month. Mr. Barber, a top aide to Ms. Giffords, announced his candidacy to run in a special election to serve as a replacement for the Arizona Democrat who was wounded in a shooting rampage. (Associated Press)

Rep Gabrielle Giffords, Arizona Democrat, tours the Gabrielle Giffords Family Assistance Center, one of her favorite charities, with staffer Ron Barber in Tucson, Ariz., last month. Mr. Barber, a top aide to Ms. Giffords, announced his candidacy to run in a special election to serve as a replacement for the Arizona Democrat who was wounded in a shooting rampage. (Associated Press)