washington deadly mass shoot u.s. history prompt call sunday members congress legislation tighten control weapons sales although slim hop much change 50 people kill gay nightclub florida democratic senator robert casey say would announce bill monday would ban anyone convict misdemeanor hate crime own firearm current law felony convictions prohibit buy possess gun convict misdemeanor hate crimes casey plan make announcement home state pennsylvania meet members pittsburgh lesbian gay bisexual transgender community lawmakers include republicans seek gun restrictions early mass shoot even minor change fail gain enough support become law back powerful gun lobby many members congress see control weapons sales threat americans constitutional right democrats also call congress act sunday attack orlando strong term richard durbin illinois senate democrat say kill would prompt debate action bottom line allow dangerous people buy gun america get change say democratic senator chris murphy say epidemic gun violence would continue congress act also say lawmakers share responsibility congress become complicit murder total unconscionable deafen silence say statement happen epidemic continue without end congress continue sit hand nothing again gunman kill 20 children six staff members sandy hook elementary school newtown murphy home state connecticut 2012. suspect orlando attacker identify omar mateen 29 u.s. citizen son immigrants afghanistan carry ar-15 style assault rifle handgun authorities say shooter newtown also ar-15 many republicans include presumptive presidential nominee donald trump focus threat islamist militants shoot cite report mateen inspire islamic state fbi say mateen twice interview make comment co-workers indicate support militant group neither lead evidence criminal activity lawmakers talk gun control florida shoot scant hope change