Ashdown reportedly had the public backing of both the United States and Britain, as well as Afghan President Hamid Karzai's initial approval, but Karzai began to raise objections publicly to Ashdown last week at the World Economic Forum in Davos, Switzerland.
On January 27, Ashdown put an end to the speculation by announcing that he had withdrawn his candidacy, saying he lacked support from the Afghan government.
"I didn't ask to do this job. It was only with reluctance and after having been persuaded by the American government, and with the agreement of President Karzai at the time, and at the request of UN Secretary-General [Ban Ki-moon] that I agreed to do it," Ashdown told the BBC. "So I am delighted to be able to return to where I was when this job was first [suggested] in October last year -- my garden and my grandchildren."
Ashdown said that "something has happened" that prompted Karzai to change his mind since they spoke about the job in Kuwait in late December, suggesting that Karzai's reversal "has far more to do with internal Afghan politics than...with the international community."
Ashdown said that "we can all speculate about why President Karzai has changed his mind," and stressed that he "wouldn't have dreamed of undertaking this job unless [Karzai] agreed that I should do so."
"I think there was a sense of mistrust in Afghanistan that Mr. Ashdown might come with some powers that could have been considered as interference in Afghanistan's internal affairs."
Afghan Foreign Minister Rangin Dadfar Spanta appeared to confirm the view that domestic concerns were behind Kabul's volte-face. Spanta told reporters on January 27 that Kabul's objections were neither about Ashdown personally nor about his nationality. Rather, Spanta said, Kabul was concerned about what he called "a negative atmosphere" created around the idea of a UN official having the role of a super envoy.
Ali Ahmad Jalali, Karzai's former interior minister and a noted expert on Afghan diplomatic affairs, told RFE/RL's Radio Free Afghanistan that there were fears in Kabul about how much power the next UN envoy would have over decisions made by the central government.
In particular, Jalali said, there were concerns that Ashdown would have powers over Kabul's decisions similar to the veto powers he excercised as the international community's high representative in Bosnia-Herzegovina.
"I think there was a sense of mistrust in Afghanistan that Mr. Ashdown might come with some powers that could have been considered as interference in Afghanistan's internal affairs," Jalali said. "It was considered that he might have the same level of power that he previously had in Bosnia."
Jalali noted that as the international community's top man in Bosnia-Herzegovina, "Ashdown had this competence to decide or give an idea over the appointment of government officials, but the situation in Afghanistan is different than Bosnia."
He contrasts Bosnia's UN-imposed tripartite presidency with the system that Afghanistan has put in place since the U.S.-led toppling of the Taliban in late 2001. "Afghanistan has an elected president and an elected parliament," he said. "And the country is united."
Indeed, as the international community's high representative in Bosnia-Herzegovina, Ashdown had dismissed Dragan Covic -- the Bosnian Croat politician who was elected in October 2002 to serve in the three-member presidency. Ashdown ordered the dismissal after Covic was indicted on charges of financial corruption.
But for his part, Ashdown rejected media reports that he had sought powers over the Afghan government that would have changed the role of the UN envoy in Afghanistan to that of a "super envoy." "I negotiated these mandates first off. And we've agreed them with Ban Ki-moon," he said.
Ashdown stressed to the BBC that the mandates had been agreed with Secretary-General Ban and that "the question of having the same powers as I had in Bosnia was never in question." He added, "If they had been offered, I would have rejected them."
"The government of Afghanistan is a sovereign government. It is a proud nation. And President Karzai is its president," Ashdown said. "Our job was to assist the government in Afghanistan to do its job -- at President Karzai's request, initially."
He described the envoy's role as being "all about coordinating the international community to support President Karzai."
Ashdown said the powers he insisted upon would have given him greater ability to coordinate the work of different UN relief agencies within Afghanistan -- including the World Food Program, the World Health Organization, the UN Children's Fund (UNICEF), and the UN High Commissioner for Refugees.
Reports claimed the next UN envoy would not have powers over NATO forces that are now in Afghanistan on a UN mandate to assist Karzai's government.
Amid the search for a new candidate, reports from Kabul said senior Afghan officials had expressed interest in another Briton -- General John McColl -- serving as the UN special envoy to Afghanistan. McColl led the first International Security Assistance Force mission in Afghanistan and was Britain's special envoy for the counternarcotics effort there. McColl is currently NATO's deputy supreme commander in Europe.
(RFE/RL's Radio Free Afghanistan correspondent Mustafa Sarwar contributed to this report from Prague.)