If election authorities invalidate enough ballots to bring President Karzai's total below a majority then he and Abdullah would face each other in a run-off.

VOA: standard.2009.09.12

If no candidate receives more than half of the total votes a run-off between the two top contenders is to be held in early October.

VOA: standard.2009.08.23

Late on Tuesday, the election commission announced that the spoiled ballots would count in the overall vote total, increasing the likelihood of a run-off between the top two candidates, news agencies report.

BBC: Kenya elections: Electronic system slows count

But Nagin's total fell short of the majority needed to avoid facing a run-off with Lt.

NPR: Nagin Faces New Orleans Mayoral Runoff

To avoid a run-off, the president needs to win 50% of the total vote or 40% plus a 10-point margin over the second-placed candidate.

BBC: Ecuador election: President Rafael Correa wins new term