Afghan President Hamid Karzai's main election challenger said Sunday that he will withdraw from a planned Nov. 7 runoff, casting new doubts on the legitimacy of the Afghan government as the Obama administration debates U.S. strategy in the region.

Iran sidestepped a Friday deadline on a U.N.-drafted agreement that would ship much of the country's uranium to Russia for enrichment, saying it would prefer instead to buy nuclear fuel from foreign suppliers for a reactor to make medical isotopes.