First results are due Tuesday in Afghanistan's hotly contested election, which has been marred by allegations of fraud and tensions as President Hamid Karzai and his main rival claimed the lead.
Officials should release partial results from Tuesday afternoon, but the Electoral Complaints Commission (ECC) has warned the final result, due next month, could be swayed by investigations into some of the 225-recorded abuses.
The United Nations threw its full weight behind the ECC's investigations and appealed for patience.
"It is not my job to define how significant and how widespread those irregularities have been. That is up to the process that now follows and where the ECC will play a critical role," UN special envoy Kai Eide said.
The Independent Election Commission (IEC) will release results piecemeal, with spokesman Noor Mohammad Noor saying around 10 percent of preliminary figures will be announced on Tuesday.
Questions have been raised about the impartiality of the IEC, as its chief officer Azizullah Lodin is a former advisor to Karzai, who is hoping to win another five-year term and appointed him by decree.
Karzai's main rival for the presidency, Abdullah Abdullah, as well as some independent has voiced the concerns election observers and US-based Human Rights Watch.
But a Western diplomat, speaking on condition of anonymity, said: "It's true the IEC has certain tendencies but they are not perhaps as active in the alleged fraud as some witnesses say."
Karzai had been tipped to easily clinch a second term. But a strong campaign by his former foreign minister Abdullah and reports of low turnout in the president's southern stronghold have fuelled speculation of a run-off.
Abdullah has alleged widespread rigging in favour of the 51-year-old incumbent, though some observers have said he may be positioning himself for defeat and a role in the political opposition.
In this case Abdullah could agree not to push his complaints about irregularities -- accusations of massive fraud, low turnout and scarcity of observers -- and instead accept a gentlemen's agreement, diplomats said.
A spokesman for Abdullah, who campaigned on constitutional reform, left the door open to him becoming Afghanistan's first real opposition leader.
"Dr Abdullah remains committed to his principles and goals," the spokesman, Sayed Aqa Fazil Sancharaki, told AFP.
"This is to bring change -- to amend the constitution, to change the system from presidential to parliamentary, and elected governors," he said.
The result could effectively divide the north and the south of the country, as Abdullah has his powerbase in the north among ethnic Tajiks, while Karzai has strong influence in the Pashtun-dominated south.
Analysts point to possible difficulties if a definitive result is delayed by investigations into irregularities. The ECC has said that 35 of the 225 complaints have been given high priority and could affect the final outcome.
"It will be problematic if the results drag out," said Haroun Mir, from Afghanistan's Centre for Research and Policy Studies.