Some wonder how far Iran's opposition leader is willing to go. They note that as premier, he was sidelined by his inability to play factional politics. Backers say he is an open-minded technocrat. Iran's economy stood in shambles and its international status was at a nadir. Disturbed by the leadership of then-President Ali Khamenei, Prime Minister Mir-Hossein Mousavi wrote him a letter and threatened to resign from his high-ranking post, according to news accounts at the time.