The country's first democratic transfer of power has been engulfed in a dispute over alleged fraud, wrecking hopes that the election would be a key achievement of the US-led military and civilian aid effort since 2001.
Instead, the battle between Abdullah, a former anti-Taliban resistance fighter, and Ashraf Ghani, an ex-World Bank economist, threatens to spark a spiral of instability as NATO troops pull out and violence increases nationwide.
But the UN-supervised process only triggered another outbreak of disagreements, and Abdullah's campaign on Sunday refused to rejoin after repeated stoppages.
"The commission waited yesterday and today, but we are half through the day and Dr. Abdullah's observers are not here," Noor Mohammad Noor, the Independent Election Commission (IEC) spokesman, told reporters.
"We have decided to continue the process without any further interruptions."
"Our negotiations with the UN are ongoing," Abdullah's spokesman Mujib Rahman Rahimi said without giving any further details.
