Vice President Joe Biden speaks with former Rep. Gabrielle Giffords, D-Ariz. and Rep. Ron Barber, D-Ariz., during the dedication of a room in the Capitol Visitors Center to slain congressional staffer Gabriel Zimmerman on Capitol Hill, in Washington, Tuesday, April 16, 2013. Zimmerman died two years ago in the Tucson, Ariz., attack that critically wounded Giffords and took six lives. (AP Photo/Jose Luis Magana)