Following widespread fraud in the August first round, Dr Abdullah and his
backers have demanded a list of anti-fraud measures.
have said he will boycott the November 7 second round if measures he
has called a "minimum" needed to avert a repeat of pro-Karzai
vote-rigging are not enacted.
Mrs Clinton's comments came amid signs the coalition is no longer expecting a
second round to take place and is instead seeking to resolve the political
limbo gripping Afghanistan as quickly as possible.
The Abdullah camp said it would announce whether their candidate would pull
out of the run-off at a 9.30am (5.00am GMT) Kabul rally on Sunday, but an
official added: "We will not participate in an election which is not
transparent and fraud-free."
Diplomats have told the Sunday Telegraph they estimate the chances of a second
round proceeding to be less than half and falling.
London and Washington are hoping Dr Abdullah will retire "graciously"
as an angry boycott would instead risk ethnic violence as his Tajik backers
refuse to recognize the result and order their supporters onto the streets.
A two-man run-off was ordered after the disqualification of nearly a million
fake Karzai votes meant neither had crossed the 50 per cent threshold
Mrs Clinton said the withdrawal of a candidate would not be "unprecedented"
and would not affect the legitimacy of the vote.
She said: "We see that happen in our own country where, for whatever
combination of reasons, one of the candidates decides not to go forward.
"I don't think it has anything to do with the legitimacy of the election."
Afghanistan's supreme court may be called to rule on whether a second round
would be needed in such a case, but few doubt the Karzai-appointed court
would back his victory.
Dr Abdullah had demanded the sacking of Azizullah Ludin, chief electoral
organiser, the suspension of three ministers and closer scrutiny of polling
However, none of his key conditions have yet been met and international
officials have said the second round is likely to be just as tainted by
fraud as the August 20 poll.
The Karzai-appointed Independent Election Commission (IEC) has refused to sack
staff and has said it will open more polling centres in the second round,
despite UN and international requests to stick to fewer, better-observed
Dr Abdullah had accused Mr Karzai of using the state apparatus to swing the
One election observer said the limited concessions made to prevent further
fraud were "ludicrous" and a second round would be a "pretence
of a free and fair election" He said: "Stand by for the chorus of
'Afghanistan is not Sweden.'"