Andullah in Kabul. (AP)

Kabul, Oct. 31: A presidential run-off election planned for November 7 seemed headed for collapse today, with the main challenger to President Hamid Karzai, former foreign minister Abdullah Abdullah, widely expected to pull out of the race.

Abdullah suddenly cancelled a trip to India today.

A campaign spokesman for Abdullah would not comment on his plans but said he would announce his decision tomorrow. However, several sources close to the candidate said he had no option but to boycott the contest because Karzai had not met his demands to fire the top election official and take other measures to reduce fraud.

“We don’t want to boycott, but Mr Karzai has not accepted any conditions, so he left us with no other choice,” said one member of Abdullah’s political team. “There is no guarantee that a second round would be free and fair. It would only create more problems than it solves.”

The prospect of Abdullah’s withdrawal could plunge Afghanistan into an even deeper political crisis after weeks of mounting tension and uncertainty over how to form a new government after Karzai’s victory in the August 20 presidential election was found invalid because of widespread fraud.

A cancelled or marred run-off would also further complicate matters for the Obama administration as it nears a decision on whether to significantly expand its military commitment to the war against Afghan and Qaida insurgents.

US officials had pressed Karzai hard to accept the run-off, hoping to produce a more credible election and resulting government, despite widespread concerns that the second round would also be marred by fraud and insurgent attacks.

Secretary of state Hillary Rodham Clinton, who arrived in Abu Dhabi early today for a meeting with Palestinian President Mahmoud Abbas, played down the importance of a possible Abdullah withdrawal, saying that his decision was a “personal choice which may or may not be made”.

Asked whether a run-off would be legitimate with only one candidate running, Clinton said that “other countries” had faced similar situations. “We see that happen in our own country where for whatever combination of reasons one of the candidates decides no to go forward. I don’t think it has anything to do with the legitimacy of the election,” Clinton said.

It was neither legally nor politically clear today what would happen if Abdullah does quit the race. Election officials said that they were still preparing to hold the vote, that Afghan security forces were ready to protect the voters, and that neither candidate had the right to withdraw at this late date.

But analysts said most of the possible options — cancelling the vote, having Karzai declared de facto President, having him run alone or postponing the race and substituting the third-highest vote-getter for Abdullah — would either leave the country in political limbo or Karzai as head of a weak and illegitimate new administration.

“The situation is both depressing and complicated,” said Ahmed Nader Nadery, chairman of the private Free and Fair Elections Foundation. “The law is silent on what to do in this situation, and whatever happens is likely to bring us more deeply into trouble, because we will probably end up with a President who did not get the minimum number of votes in a fair election.”

The foreign minister has delayed announcing his decision for the past several days as private negotiations and meetings were held involving Karzai, Abdullah and their political aides and allies. But sources close to the discussions told various media outlets that talks between the two rival leaders collapsed yesterday, after Karzai said he would not meet Abdullah’s demands.