According to reports from Kabul, U.S. envoy Richard Holbrooke is believed to have had an argument with Afghan President Hamid Karzai -- with Holbrooke complaining alleged fraud by members of Karzai's own campaign team, as well as by other candidates.
Sources say Karzai reacted angrily to the accusations, while a spokesman denied any heated exchange took place.
A spokeswoman for the U.S. Embassy in Kabul is denying reports that Holbrooke and Karzai shouted at one other, or that Holbrooke angrily stormed out of the meeting.
A U.S. official in Washington, who spoke on condition of anonymity, said the meeting was "difficult" and that there had been some "sharp exchanges." That official says Holbrooke's points during the meeting were that Afghanistan must respect the electoral process, be patient, and respect the results.
U.S. State Department spokesman Philip Crowley says it is too early for Washington to announce suspicions that the election outcome was altered by fraud.
"We're in a delicate time here," Crowley said. "We're going to wait and see what the results of the elections are. We're going to wait and see what the composition of the Afghan government is. As a strategic imperative, we are working hard with the international community [and] with the sitting Afghan government to create institutions that will meet the needs of the Afghan people."
To be sure, complaints of electoral fraud have been widespread.
Karzai's main competitor, former Foreign Minister Abdullah Abdullah, charges that there was a vast, state-engineered campaign of fraud in favor of Karzai. Still, Abdullah has urged his supporters to be patient and to work through the electoral system. Other candidates have made similar complaints.
Expectations For Second Round
Jean MacKenzie, the director of the Kabul office of the Institute for War and Peace Reporting, told RFE/RL that it was widely expected that Karzai would not get enough support to win reelection outright in the first round.
To do so, Karzai needed to win at least 50 percent of the ballots cast. For weeks before the vote, a second-round ballot was being predicted by the European Union, the U.S. Embassy, and other international players in Afghanistan.
MacKenzie says that it would have been easy for local election officials to alter results at their polling station in case of low voter turnout. If only 100 out of 500 eligible voters cast a ballot on election day, she says, polling center administrators would have been able to cast up to 400 ballots for the candidate of their choice.
Marvin Weinbaum, a former U.S. State Department analyst who monitored last week's presidential and provincial Afghan elections, told RFE/RL that he has seen every indication that fraud was widespread.
"Everyone knows that an election in Afghanistan was going to have a certain amount of fraudulent voting," Weinbaum said. "There is no way to avoid this. The question has been all along: Would that be of such a scale -- would that be of such a dimension -- that subjectively, the public and the international community would say that the fraud which took place was too much?"
Two early batches of vote tallies show Karzai with nearly 45 percent of the vote, compared to 35 percent for Abdullah. His lead was expected to grow further as the tallying continues. But that may now be delayed as the electoral commission investigates the fraud allegations further.
Weinbaum said that at this point in time for Afghanistan, a credible election is "absolutely critical for the larger challenge that the Afghan government and international community face" in battling the Taliban insurgency.
"If this election lacks complete credibility -- if it is not accepted [by the Afghan people] and if the president is not seen as legitimately holding his office -- this will seriously undermine the military campaign," Weinbaum said.
"[It also will undermine] the campaign to bring better governance to the countryside and the campaign to bring development to the countryside. This is why this election is so important."
Analysts say that if the official results show Karzai winning outright in the first round, suspicions among Afghans about vote fraud would be raised. In that case, confidence in the democratic process among ordinary Afghans could be restored only if Afghanistan's electoral complaints commission disallowed enough votes to bring Karzai's total below the 50-percent threshold.
"The one way to overcome this may very well be to allow it to go on into a second round -- where you have a face-off between the top two candidates -- and then to bring in safeguards for the second round that were not in place for the first round," Weinbaum said. "And that probably means a larger role for the international community in the monitoring of the election. This election was given over entirely to the Afghans themselves."
MacKenzie agrees that a second-round vote would help alleviate suspicions about fraud in the election process. But she says it also would raise additional complications.
"Final results will not be announced until the 17th of September," MacKenzie said. "And by law, the [second-round] poll has to be two weeks after that. So it's not a lot of time to print ballots, get them shipped out, and get all of the arrangements in place that they will need to do."
"There are going to be security implications for this," MacKenzie continued. "There could very well be protests and/or violence. There are going to being logistical implications for this. And [preparations for a second round vote would be] all happening during the month of Ramadan, which makes it all much more complicated in the Afghan context."
Still, with trust in the elections very low even before the vote, MacKenzie and others conclude that a second-round ballot may be necessary to convince many Afghans that democracy is not a sham.
RFE/RL correspondent Abubakar Siddique contributed to this report.