Renard Sexton runs the numbers on electoral fraud:
Using our conservative affected-vote estimates, the situation remains fairly damning for Hamid Karzai. Assuming that the results are equal to or less favorable than our estimates, it seems likely that a runoff will ensue. With just four percent of cushion, it would take a miracle for him to walk away with a majority after this, where 20 percent of the vote is fraudulent, much from his tally. Dr. Abdullah Abdullah is in the strongest position he has been in thus far, and could conceivably win a run-off held in strict conditions.
Of course, strict conditions we do not have in Afghanistan, where winter is rapidly approaching. If another round of voting is ordered, it could be difficult or impossible to complete before the freeze brings movement around the country, outside of major cities, to a halt. Perhaps a coalition government or tribally negotiated solution is in store?
Further thoughts on the situation by J Alexander Thierat of Foreign Policy.