The election commission could discard more than 700,000 of the 2.7 million votes cast in the poll because they fail to meet new rules aimed at combating fraud.

The hitch could undermine a vote that organizers hoped would mark a turnaround from parliamentary elections a year ago that were tainted by widespread organizational and technical issues and the previous, disputed presidential poll in 2014 that threatened to tear the country apart.

The commission used computerized voter lists and biometric voter verification in an effort to prevent the kind of large-scale ballot stuffing that tainted those elections. It has said it will only validate ballots that meet its criteria.

The commission said the biometrically verified turnout from 85 percent of polling stations was around 1.7 million. Observers said once the data from the remaining polling stations is added, the voter turnout will drop to around 2 million and then fall further once duplicate ballots are weeded out.

"It will further lower the turnout, which is already the lowest compared to past elections," said Ali Adili, a researcher at the Afghanistan Analysts Network (AAN), an independent think tank in Kabul. "But it might help produce a clean vote."

Dramatic Drop

According to the figures released by the election commission on October 14, the provinces with the biggest percentages of unverified votes were the northern province of Baghlan with 85 percent, the eastern province of Paktia with 77 percent, and the southern provinces of Kandahar and Helmand, with 72 percent and 68 percent respectively.

Even before the commission released its updated figures, the seemingly inflated number of votes and even turnout in these provinces had raised suspicions that the outcome of the election could be significantly affected by fraud.

To highlight the environment of distrust, the two front-runners in the election -- incumbent Ashraf Ghani and current Chief Executive Officer Abdullah Abdullah -- have each claimed victory and signaled they will not accept defeat, a scenario that could trigger a political crisis and spill over into violence.

In 2014, their disputed runoff threatened to spark a civil war before they agreed to a power-sharing agreement brokered by the United States.

The sides have accused each other of fraud and sparred over the criteria used to separate valid from invalid votes. Abdullah has said only biometrically verified votes should be counted, while Ghani's campaign has been more open to also counting unverified ballots.

Their respective supporters have also bickered over the new figures. Abdullah's supporters say most of the provinces with the highest numbers of unverified votes were in the south and east, predominately Pashtun areas that are likely to vote for Ghani. Meanwhile, Ghani's supporters say unverified votes were also recorded in the north, Abdullah's support base.

Allegations of fraud have surged, with the electoral complaints commission recording more than 4,000 complaints.

As the level of mistrust grows, Adili says the legitimacy of the election could come down to the election commission's complicated process of "tallying and cleaning votes."

Potential Delays

The election commission is expected to release the preliminary results of the election on October 19. But it has said there might be a delay of up to a week.

Commissioners said they were still uploading the biometric data from devices and reviewing result sheets from the nearly 5,000 polling centers.

The tally has been disrupted by technical troubles and reported attempts to hack into the commission's servers. Before the preliminary results can be released, the commission must discard invalid votes.

Alice Wells, the top U.S. State Department official for South Asia, who visited Kabul on October 15, said the election commission had a "challenging task to review votes, process complaints, concerns, and allegations of fraud," adding that it was better to "deliver an accurate result rather than a rushed one."