Afghanistan's Independent Electoral Commission (IEC) has said it will announce final results of August's disputed presidential elections.
The announcement comes a day after a UN-backed panel, the ECC, said it had found clear evidence of fraud.
President Hamid Karzai will accept the IEC's results, his spokesman says.
But it is not clear whether the IEC, which is widely believed to be pro-Karzai, will follow the UN panel's recommendations.
Initial results released last month gave Mr Karzai nearly 55% of votes, and his main rival Abdullah Abdullah 28%, suggesting the president had won outright.
But the ECC said that after fraudulent ballots were discounted, Mr Karzai's total was reduced to below 50%, indicating that a second round was needed.
Mr Karzai has previously refused a run-off, insisting he won the election outright. He could also seek a power-sharing deal with Mr Abdullah.
Correspondents say there are concerns that a run-off could lead to further fraud, violence and ethnic strife.
There is also limited time available, as much of the north of the country becomes inaccessible in winter.
"Our commissioners are meeting now to discuss the figures sent by the ECC and will announce a final decision today," IEC spokesman Noor Mohammad Noor said.
On Monday the ECC said it had found "clear and convincing evidence of fraud".
The panel ordered that ballots from 210 polling stations across the country be discounted.
According to respected US-based group Democracy International, Mr Karzai's share of the vote has now fallen to 48.29%, and Mr Abdullah has 31.5%.
About 1.3 million votes for Karzai were invalid, about a quarter of the total cast, the group added.
Need for legitimacy
In the last few days Western leaders and diplomats have engaged in a rapid round of diplomacy to get Mr Karzai to accept the election results.
Washington - which has been debating a request for 40,000 more US troops for Afghanistan - has put any decision on hold for the time being.
The BBC's Barbara Plett at the United Nations says the Americans - and their Nato allies - are looking for a second round or a national unity government.
They say the government must be legitimate if the US public is to be convinced it is worth sending more soldiers to fight in Afghanistan.
With violence at its worst levels across Afghanistan since the Taliban were ousted in 2001, there are warnings that the ongoing political paralysis will only embolden the militants.
