Sudan and Western powers plunged into a war of words over Darfur on Friday, with Khartoum countering U.S. charges of genocide by saying Washington was playing electoral politics with a humanitarian crisis. Sudan's rulers said a finding by U.S. President George W. Bush and Secretary of State Colin Powell of genocide in Darfur was "an isolated position" made in the heat of a presidential election to win African-American votes. "They should not use a humanitarian problem for political agenda," Foreign Minister Mustafa Osman Ismail told Reuters during a visit to South Korea. "We know that an election is going on. We know the political parties, the Republicans and Democrats, are competing for the votes of African-Americans," Ismail said.