For Toomey, the Giffords backing is the latest dose of support that his campaign hopes could help him broaden his appeal. Former New York Mayor Michael Bloomberg also endorsed Toomey this month through his Independence USA PAC, which focuses on gun laws. And in an ad from the group, Erica Smegielski, the daughter of the slain Sandy Hook principal, lauds Toomey for crossing party lines to support gun-control bills.