FILE - In this Jan. 30, 2013 file photo, former former U.S. Rep. Gabrielle Giffords, who survived a gunshot to the head in 2011, during a mass shooting in Tucson, Ariz., sits ready with her husband, retired astronaut Mark Kelly, at a Senate Judiciary Committee hearing on Capitol Hill in Washington to discuss legislation to curb gun violence after the death of 20 schoolchildren in the shooting rampage late last year in Newtown, Conn. Giffords told the committee that Congress must reform the nation's gun laws, and Kelly got into a terse discussion at the witness table with National Rifle Association Executive Vice President Wayne LaPierre. (AP Photo/J. Scott Applewhite, File)

FILE – In this Jan. 30, 2013 file photo, retired astronaut Mark Kelly, left, husband of former Arizona Rep. Gabrielle Giffords, who survived a gunshot to the head during the mass shooting in Tucson, Ariz., in 2011, shakes hands with National Rifle Association CEO Wayne LaPierre after they testified about gun violence and legislation during a hearing on Capitol Hill in Washington. Kelly got into a terse discussion at the witness table with LaPierre, and Giffords told the committee that Congress must reform the nation’s gun laws. Gayle Trotter, senior fellow with the Independent Women's Forum, who also testified, stands at center. (AP Photo/Susan Walsh, File)

FILE – In this Jan. 30, 2013 file photo, retired astronaut Mark Kelly, left, husband of former Arizona Rep. Gabrielle Giffords who survived a gunshot to the head during the mass shooting in Tucson, Ariz., in 2011, shakes hands with National Rifle Association CEO Wayne LaPierre after they testified about gun violence and legislation during a hearing on Capitol Hill in Washington. Kelly got into a terse discussion at the witness table with LaPierre, and Giffords told the committee that Congress must reform the nation’s gun laws. Gayle Trotter, senior fellow with the Independent Women's Forum, who also testified, stands at center. (AP Photo/Susan Walsh, File)

FILE - In this Jan. 16, 2013 file photo, President Barack Obama, accompanied by Vice President Joe Biden, talks about proposals to reduce gun violence at the White House in Washington. 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 in December 2012 at an elementary school in Newtown, Conn. In response, gun-rights advocates have accused Obama and others of ignoring the Second Amendment rights of Americans. (AP Photo/Charles Dharapak, File)