Former Rep. Gabby Giffords, D-Ariz., and her husband Mark Kelly at Wednesday's Senate hearing about gun violence. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images

President Obama, accompanied by Vice President Joe Biden, talks at the White House on Jan. 16 about proposals to reduce gun violence. Obama has called for a ban on military-style assault weapons and high-capacity ammunition magazines and is pushing other policies in the wake of the mass shooting last month at an elementary school in Newtown, Conn. Charles Dharapak/AP hide caption

itoggle caption Charles Dharapak/AP

A photo taken in January shows part of a cache of seized weapons displayed at a news conference in Phoenix. In July, the Justice Department announced new rules requiring gun dealers to report multiple sales of semi-automatic rifles. Matt York/AP hide caption

itoggle caption Matt York/AP