Lack of evidence is evidence of nothing.

The Petraeus scandal and the Benghazi affair are both still unraveling.  They are both extremely important stories, no doubt, having foreign policy as well as national security implications.  It may turn out that the White House mishandled one or both.  Nevertheless, there is no evidence of such malfeasance or incompetence as yet.  This does not prevent the GOP from creating certain conspiracy theories prior to the presentation of any evidence.  At first, they presented arguments from coincidence, not realizing that that is a self-defeating argument--if it were a coincidence, it cannot have been an orchestrated conspiracy (look up the definition of coincidence).  But it seems certain commentators are taking it down a notch.  Why look for evidence when a lack of evidence will work just as well. 

In logic, we call this an appeal to ignorance--the attempt to use lack of evidence as evidence.