Talks between Afghan President Hamid Karzai and challenger Abdullah Abdullah have broken down, and Abdullah is likely to pull out of next week's presidential runoff, a person with knowledge of the talks said.
An announcement could come as early as on on Saturday but more likely on Sunday, the person said on Friday.
Abdullah, who was once Karzai's foreign minister, put forward several conditions earlier this week for the November 7 election to be credible, but intensive talks between the two candidates and their supporters over the past few days broke down yesterday, the person, a Westerner, said on condition of anonymity because the discussions were private.
Abdullah gave Karzai until today to agree to the conditions, the person said.
The political stalemate in Kabul comes as President Barack Obama has been meeting with his advisers to try to determine US strategy in Afghanistan, including troop levels.
A weakened Afghan government will make it harder for Obama to get public support for his efforts.
The runoff election in Afghanistan became necessary after widespread fraud in the first-round of voting in August resulted in thousands of Karzai's ballots being invalidated, pushing him below the required 50 per cent margin to win.