Regardless of whether or not Enron donated to both sides, the real question is what happens now. Since Bush is in charge of the Executative Branch, prosecuting (or failing to prosecute) falls directly (or indirectly) on him.
As yet, to the best of my knowledge, no charge have been filed against Enron, Lay, Skillings or Fastow. (Yet it is a crime for a company to take/use funds from it's employee's pension).
(And note: last I checked, the Clayman Islands STILL hadn't received any official requests for help in an investigation.)