Iran is locked in a classic power struggle, pitting the house of Khamenei against the house of Khomeini. It has been simmering since Khamenei was appointed Supreme Leader in 1989, but it is only now that Khomeini's heirs have chosen to finally fight back against a complete takeover of the regime by Khamenei and the Revolutionary Guards. The Khomeinists were mistakenly convinced that if they could muster a 70% turnout and win the elections, Khamenei would not dare throw out the results.
Now that Khamenei has refused new elections, the opposition has switched from challenging the June 12 election results to attacking the legitimacy of Khamenei himself. They are counting on Khamenei to continue cracking down on demonstrators, arresting larger numbers of opposition supporters and eventually jailing the leaders. In the end, they believe, Khamenei will so antagonize Qom's ayatullahs that the country's clerical leadership will issue a fatwa condemning Khamenei and the June 12 election. Such a fatwa would strip Khamenei of any legitimacy as Iran's clerical Supreme Leader, eroding his support in the Revolutionary Guards. Already, the enlisted men in the ranks of the Revolutionary Guards are uneasy about suppressing the demonstrations. Its rank and file, like other Iranians, have suffered from the poor economy under Ahmadinejad. Reportedly, there have also been arrests inside the regular army. If true, it's a dark omen for Khamenei. A countercoup may just be on the cards.
http://www.time.com/time/world/article/0,8599,1912970,00.html
All it will take is one bullet.