The international Electoral Complaints Commission Monday released a report citing "clear and convincing evidence from fraud" in the Aug. 20 voting in Afghanistan. The panel ordered enough ballots discarded that Karzai's announced total of 54 percent of the vote was reduced to less than 50 percent.
The Afghan Constitution, in such cases, calls for a runoff between the top two vote-getters. That would pit Karzai against former Foreign Minister Abdullah Abdullah. The two had reportedly been in talks about a power-sharing government rather than having a new election.
Afghan elections officials said they were prepared to have the second vote in just more than two weeks.
The Obama administration said it is waiting for the political smoke to clear in Afghanistan before deciding on troop levels in the country. About 68,000 U.S. troops have been committed to the Afghan effort and commanders are asking for 40,000 more troops to stabilize the country in the face of a Taliban-led insurgency.