How do you solve a problem like Mugabe?

The United States has begun pushing for economic sanctions and travel bans against Zimbabwean President Robert Mugabe and his administration after an election last Friday speckled with intimidation, violence, and corruption.  China, a long-time ally and arms supplier of Zimbabwe, is pushing back, claiming that this is an internal matter and imploring the United Nations for more diplomatic action toward Mugabe.  

Governments aside, what do human rights groups have to say on how best to handle Mugabe's insidious seizure of power?  Human Rights Watch's argument appears to be a hybrid.  HRW is calling for the African Union to reject Zimbabwe's election, including the imposition of sanctions, and to press for peacekeepers to end the recent violence.  Sounds plausible, but how likely is it that the AU will actually take "the strongest possible action" against Mugabe?  Read HRW's recommendations here.