A politial storm is gathering over the Southern African Development Community (Sadc) on whether Zimbabwe should be on the agenda of the regional bloc's forthcoming summit in Windhoek, Namibia, next month.Diplomatic sources said this week the potential row pits President Robert Mugabe's Sadc allies against those who support Prime Minister Morgan Tsvangirai. Mugabe usually resists having Zimbabwe on the agenda of such meetings, while Tsvangirai wants it to be discussed. A similar battle erupted last year just before the Sadc summit in Kinshasa on September 7-8.