US Secretary of State Hillary Clinton made clear the Obama administration will work with Afghan President Hamid Karzai should he remain Afghanistan's leader, as seems all but certain.
"It is now a matter for the Afghan authorities to decide on a way ahead that brings this electoral process to a conclusion in line with the Afghan constitution," Clinton said in a statement e-mailed to reporters on Sunday while travelling in Morocco.
"We will support the next president and the people of Afghanistan, who seek and deserve a better future."
As Obama weighs whether to approve a request from his top commander in Afghanistan for a 40,000 increase in US troops, Abdullah's exit from the 7 November vote threatened to raise doubts about the legitimacy of Karzai's government.
The Afghanistan war has become unpopular with the American public, with violence at its worst levels since US-backed Afghan forces ousted the Taliban in 2001.
Many of Obama's Democratic allies in Congress are wary of a troop increase, while Republicans accuse him of dragging out deliberations over strategy. Some question whether Washington has a credible partner to work with in the Afghan government.
Karzai's camp ruled out a coalition with Abdullah, dashing hopes of a way out of the impasse.
Still unclear is whether the 7 November run-off would go ahead with Karzai as the only candidate, given the expense involved in the vote and potential security risks.
Afghan election officials said the run-off would take place and US officials said it was up to Kabul to decide.
Dealing with corruption
"We're going to deal with the government that is there and obviously there are issues we need to discuss, such as reducing the high level of corruption there," senior Obama adviser David Axelrod told the CBS programme 'Face the Nation'.
Axelrod said Abdullah "made a political decision" to quit the run-off and it was likely he would have been defeated.
In her statement, Clinton urged Abdullah to "stay engaged" and work for peace in Afghanistan.
Abdullah left the door open for future discussions but said no deals had been struck in return for his withdrawal, seen by diplomats as one way to spare the country more uncertainty that discredits the government and can only aid the insurgency.
"This decision has not been made in return for anything or for anybody," Abdullah said.
His voice faltering and his eyes welling with tears, Abdullah told hundreds of supporters, including white-bearded tribal elders, in a giant tent used for grand assemblies that he had reached the decision "in the interests of the nation".
"As far as I'm concerned, the decision I have reached is not to participate," he later told reporters. "I have strong, strong reservations about the credibility of the process."
Karzai had been favourite to win the run-off after getting more votes in a 20 August first round marred by widespread fraud. His campaign team also said the run-off would go ahead.
"Dr Abdullah's decision has disappointed us," Karzai said in a statement, adding his team would accept whatever rulings were made by the IEC and legal authorities such as the Supreme Court.
The Taliban, which have vowed to disrupt the polls again, said Abdullah's withdrawal made no difference.
"There will be no change of policy as far as we are concerned," Taliban spokesman Qari Mohammad Yousuf told Reuters by telephone from an undisclosed location.
A strong and legitimate Afghan government is central to the US strategy to quell rising Taliban violence. Obama had already delayed the strategy decision on sending extra troops to await the election result.
Karzai and British Prime Minister Gordon Brown spoke by telephone on Sunday. Brown told the BBC that Karzai, seen by many in the West as a weak leader at the head of a government riddled with corruption, wanted to issue a "unity manifesto".
"And what we've talked about is how he must first of all show people that he's tackling corruption and he's getting the right people into government," Brown said.
Abdullah said he quit because demands he had sought from the government and the IEC, including the sacking of Afghanistan's top election official, had not been met.
The run-off was triggered when a UN-led investigation found widespread fraud, mainly in favour of Karzai, had been committed during the first round.
A US official said on Saturday that Obama was unlikely to make a decision on his Afghanistan strategy before he leaves for a 10-day trip to Asia on 11 November.
General Stanley McChrystal, the commander of US and NATO forces in Afghanistan, has recommended deployment of an additional 40,000 troops next year.
Another scenario under consideration could involve adding 10,000 to 15,000 troops, a large portion of whom would be focused on increasing the training of Afghan forces. But US officials have said a number of options are under review.
There are about 67,000 US troops and 42,000 allied forces in Afghanistan.
(EurActiv with Reuters.)
