Sniper Suspect Shown in Campaign Ad By DAVID ESPO AP Special CorrespondentWASHINGTON (AP) -- John Allen Muhammad, accused in the sniper killings, has made his political debut. His image is appearing in a gun control commercial that an underdog Democrat hopes to ride to victory in New Jersey."Scott Garrett shouldn't be blamed for the sniper," says a commercial that Anne Sumers' campaign has begun airing in a district in the northern part of the state. "But Garrett's positions are the problem."The Garrett campaign sharply criticized the ad."I think it's sickening to see Anne Sumers exploiting the tragedy of the sniper...