I believe an attempt will be made and not as a false flag exercise. Recently, O went over to Afgan to speak with the CIA's dude in charge of the country over there. This was a surprise visit right after obvious conflicting communications to the guy. I say obvious because the week before he was all up in arms yelling about this and that and even making threats. It seems the executive was putting pressure on the CIA's man. The CIA will not put up with this sort of behavior from a president for long.
Oh, if it happens before the November elections it will be a lone wolf gunman with strong connections with the Tea Party.