Optimistic comments from the Iranian foreign minister suggest that an accord with West may yet be reached.
Secretary Rice has floated the idea of an interests-section office – a step down from an embassy.
Destruction of its nuclear cooling tower was important but largely symbolic.
Exxon Mobil, Chevron, and Shell are among the prequalified companies vying for contracts.
The African Union is expected to discuss the issue in Egypt Monday, one day after Mugabe declared a 'sweeping victory' in Friday's presidential runoff, which was widely condemned as a sham.
The opposition's pullout from Friday's vote raises pressure on Zimbabwe's leader.