They want to keep the evidence under wraps until after the 2012 election.
I would have to agree. If they did nothing...there would be talk of a special prosecutor requirement by December of this year, and that would hurt them greatly by the summer of 2012. By jumping in....you keep the data in a locked box. You slowball this by putting in half the analysts you’d normally use, and you use mostly rookies to ensure that they keep asking more questions rather than answering them.
The FBI will hand their case over to a federal prosecutor around December of 2012, and actual charges will be put on the books around January 2013. At that point, someone will figure out that someone high up in the administration did the “pushing” and want them tossed into the mess.