The top U.S. envoy to Africa said Thursday that Zimbabwe's opposition leader won his nation's disputed presidential election and longtime President Robert Mugabe should step down, according to The Associated Press. The opposition has claimed its leader, Morgan Tsvangirai, beat Mugabe outright March 29. Independent Zimbabwean observers also say Tsvangirai won, though not by enough to avoid a run-off _ and Jendayi Frazer, assistant U.S. secretary of state for African affairs, cited those figures when she spoke to reporters Thursday. Zimbabweans still await the results. The opposition accuses Mugabe of withholding them while he plots how to keep power and orchestrates a campaign of retribution that the opposition says has killed at least 10 of its supporters. The octogenarian Mugabe has led Zimbabwe since independence in 1980. Frazer was responding to questions about whether some kind of power-sharing agreement could resolve the impasse. «We think in this situation we have a clear victor,» she said. «Morgan Tsvangirai won, and perhaps outright, at which point you don't need a government of national unity. You have to accept the result.» Independent tallies gave Tsvangirai 49.4 percent of votes, a projection that, with a margin of error, means Tsvangirai could have won more than the 50 percent plus one vote needed for outright victory. Of Mugabe, Frazer said: «He contested for president and he lost. ... President Mugabe should respect the will of the people and allow a new president to come in.» That new president should be Tsvangirai, she added.