I ultimately blame those deaths on Obama because I think a deliberate "small footprint/don't antagonize anyone" policy led to us having people unable to defend themselves effectively. I also blame him for Gen. Ham's decision that airstrikes were not "the appropriate tool" to help out our people in Benghazi.
However, the particular example of the on-site CIA chief refusing to release the contractors to go to the consulate is something I put on him. I think he probably did it because he didn't want to expose a CIA facility/annex that was supposed to be covert, and so hoped that the locals would bail out the ambassador. Terrible decision, but I don't think it was one made with malice.