Judi and Wayne Richardson, who lost their daughter Darien to gun violence in 2010, filed an application for a referendum on background checks Monday. Richardson Family hide caption

itoggle caption Richardson Family

"I think that urban America has got to respect what rural America is about, where 99 percent of the people in my state who hunt are law abiding people," the 2016 Democratic presidential hopeful said to NPR. Lydia Thompson/NPR hide caption

itoggle caption Lydia Thompson/NPR

President Obama speaks in April after the Senate rejected a bill that would expand background checks on guns. The White House is seeking to clarify rules that bar firearm possession due to mental health problems. Manuel Balce Ceneta/AP hide caption

itoggle caption Manuel Balce Ceneta/AP

Sen. Kelly Ayotte, R-N.H., has drawn the focus of gun control proponents for voting against a bid to expand criminal background checks for gun buyers. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

Firearms for sale at a gun show in Annapolis, Md., on April 14. Andrew Harnik /The Washington Times /Landov hide caption

itoggle caption Andrew Harnik /The Washington Times /Landov