I see what you are saying here, and think you on the right sort of track. Yet the Benghazi mess might not be the best to have central focus upon. It's awkward now (but hopefully in a good way?). People in Libya, along with official "police" have moved against the militias there in effort to oust them. The killing of our ambassador appears to have been the trigger --- IF we can believe what has been broadly publicized (BBC, NY Times, various Arab language news, etc.)
However, if it could be achieved the result could be devastating for Obama because it would starkly put into place his failures across the board and make them clear as his personal responsibility, the unavoidable result of his radical leftist ideology.
The average voter would have everything, foreign and domestic, fall into place.