The Afghan Taliban are struggling to find a successor to slain chief Mullah Akhtar Mansour, militant sources said on Tuesday, with one saying the two main contenders had backed out of the leadership race. Mullah Yakoub, the Taliban founder's son, and Sirajuddin Haqqani, an implacable foe of US forces, were seen as the two front-runners for the job after Mansour was killed on Saturday in a rare American drone strike deep inside Pakistan. "Yakoub has refused to accept the role, saying he is too young for it," a senior Taliban source in northwest Pakistan said. "Mansour's deputy and operational head of the Haqqani network, Sirajuddin Haqqani, has also refused due to personal reasons." That development will complicate the job of the Taliban's supreme council, which has been holding emergency meetings since Sunday at an undisclosed location in Pakistan to find a unifying figure for the leadership post. The insurgents have yet to officially confirm the death of Mansour, which has thrown the deeply faction-ridden Taliban into disarray nine months after he was elevated to the Taliban leadership following a bitter power struggle. "The main challenge is to save the Taliban movement from being further divided," another Taliban source said, adding that supreme council members were constantly changing the venue of their meetings to avoid potential air strikes. "It will take time to reach a consensus for the leadership position." Other candidates in the fray include Mullah Abdul Ghani Baradar, the movement's former deputy who is said to be close to the Pakistani military establishment. He was jailed by Pakistan in 2010 but freed in September 2013 as part of efforts to boost Afghanistan's peace process. He has since been reported to be under house arrest by Pakistani authorities. Mullah Adbul Qayyum Zakir, considered one of the group's most violent and committed commanders, is another leading contender. The complicated search for a new leader risks igniting a new succession battle within the Taliban, which saw its first formal split last year. Many top commanders refused to pledge allegiance to Mansour, saying the process to select him was rushed and biased as they accused him of keeping founder Mullah Omar's death secret for two years. "The Taliban movement is passing through a very crucial stage. We need a conciliator not a warrior to take his place," one of the Taliban sources said, citing some of the commanders at the supreme council meetings. Meanwhile, US President Barack Obama approved the drone strike that killed Mullah Akhtar Mansour because the Taliban leader was overseeing plans for new attacks on American targets in Kabul, the Afghan capital, US officials said on Monday. While the Taliban have yet to confirm the death of their leader Saturday in a remote area in Pakistan near the border with Afghanistan, senior members of the insurgency's leadership council met to begin choosing Mansour's successor. Two senior members of the movement also said Pakistani authorities had delivered Mansour's badly burned remains for burial in the western city of Quetta. Pakistani officials, however, denied handing over a body. US forces targeted Mansour because he was plotting attacks that posed "specific imminent threats" to US and coalition forces in Afghanistan, said Navy Captain Jeff Davis, a Pentagon spokesman. A US official, speaking on condition of anonymity, later specified that the Taliban were planning new attacks against "our interests and our people in Kabul." He did not elaborate. But the administration hopes Mansour's death will have a long-term impact by pushing the Taliban to end its refusal to engage in peace negotiations with Kabul and "choose the path to reconciliation," the official said. He expressed hope that the death of Mansour will convince Pakistan to live up to its "rhetoric" and deny safe haven to the Taliban. American intelligence and military officials have long said the Pakistani military supports elements of the insurgency. But the Taliban's direction is hard to predict and hinges largely on what happens in the leadership contest and in fighting over the summer season. Mansour's death cleared "an obstacle to reconciliation," said one US intelligence official, also speaking on condition of anonymity. "But it's not clear if it clears the path for reconciliation." A second US intelligence official was more pessimistic. "It's at least equally likely that killing Mansour will destroy any chance to get the Taliban into negotiations with the (Afghan) government, not that there ever was much of one," said the second official, who specializes in South Asia and also spoke on the condition of anonymity. "His successor could be even more loathe to negotiate."