World Trade Organisation members narrow field of director-general candidates.
Jerome Luanda was arrested at the Julius Nyerere airport in Dar over money laundering allegations.
Mohamed Hussein Roble is expected to demonstrate adequate loyalty to his boss, something his predecessor was accused of lacking.
Paul Rusesabagina has been remanded for 30 days pending trial. He plans to appeal the bail verdict.
Delegates voting for 275 MPs who will in turn elect the federal president.