Afghanistan: Karzai ally to back Abdullah in Afghan runoff --- Afghan election frontrunner Abdullah Abdullah has received a major boost to his presidential campaign, with Zalmai Rassoul, a close ally of the current leader, endorsing him after withdrawing from the race. -- Rassoul was seen as the favoured candidate of outgoing President Hamid Karzai, and his support for Abdullah could be decisive in deal-making to choose Afghanistan's next leader as US-led troops withdraw from the country. -- Rassoul's own bid to become president gained little momentum and he came third with just 11.5 percent in the first round of voting, but he remains an influential power-broker. -- "I ask the people for the sake of national unity and political stability to vote for Doctor Abdullah, so that we win the election," Rassoul, who resigned as foreign minister to run in the election, told a news conference in Kabul on Sunday, the AFP news agency reported. -- He said his support could be a "balance maker" in the run-off election due next month. -- Al Jazeera's Imtiaz Tyab, reporting from Kabul, said: "Abdullah is a very happy man. If a runoff is called, he is going to need those suppporters who backed Rassoul." -- Tyab said the move could see Rassoul securing a position in the next cabinet. -- The second-round vote will pit Abdullah against former World Bank economist Ashraf Ghani in a head-to-head battle, after the two came first and second in the eight-man election on April 5. -- Neither candidate secured the 50 percent needed for outright victory. Abdullah garnered 44.9 percent and Ghani received 31.5 percent, according to preliminary results.