Incumbent hard-line President Mahmoud Ahmadinejad, who has denied the Holocaust and vowed bloodcurdling threats against the United States and to wipe Israel off the map, is being challenged by former Prime Minister Mir-Hossein Mousavi, who was an extremist prime minister through most of the 1980s but now appears a relative moderate compared with Ahmadinejad. There are two other candidates, but the race is seen as between Ahmadinejad, whose reputation precedes him, and Mousavi. If no candidate wins more than 50 percent of the vote, a runoff is scheduled for June 19.
Most opinion polls heavily favor the incumbent Ahmadinejad, but some have given widely varying results -- Ahmadinejad's support swings from 22 percent to 62 percent. On the other hand, Ahmadinejad and his supporters control the state functions of government, which puts them at a huge advantage.
The campaign has been very spirited. The central issues -- echoing last November's presidential election in the United States -- are the economy and international relations. The British Broadcasting Corporation reported that, after voting, Ahmadinejad thanked his fellow Iranians for "their goodness, for the greatness, for their selflessness, their sacrifice and for their forgiveness." What was meant by that last comment is unclear.
Mousavi said, "God willing, with the nationwide participation of the public we will see better and more beautiful days."
A quarter-century ago Mousavi was determined to export the Iranian Islamic Revolution throughout the Middle East, and he vigorously prosecuted Iran's bloody, eight-year war with Iraq not just to drive the Iraqi invaders out of Iran, but also to carry the flag of the revolution across the entire region, fulfilling the implacable vision of the Islamic Republic's founding father, Ayatollah Ruhollah Khomeini.
But Mousavi sounds very different today. Al-Jazeera television network quoted him as saying in the closing stages of his electronic campaign, "The conditions in this country have changed. The revolution has changed. There were specific conditions at the beginning of the revolution, particular motives and the motivation."
According to al-Jazeera, Mousavi now wants to ensure that Iran functions as part of the international system as a major and respected power, and even as a partner to other nations.
The position of president is no figurehead in Iran. Ahmadinejad re-radicalized the country's foreign and national security policies and pushed ahead more energetically than ever with its nuclear development programs after he succeeded President Mohammed Khatami in the 2005 presidential election. Khatami had offered two U.S. presidents, Democrat President Bill Clinton and Republican George W. Bush, to negotiate an end to Iran's programs that could develop nuclear weapons, but neither followed up on it.
Iran's current Supreme Leader, Ayatollah Ali Khamenei, backs Ahmadinejad.
If Ahmadinejad wins, global oil prices, which climbed back to $70 a barrel this week, are likely to rise again, as fears will increase that Israel may order a pre-emptive air attack on Iran's far-flung web of thousands of gas centrifuges that are working day and night to produce highly enriched uranium for nuclear weapons.
That could also happen if Mousavi wins, but the Israelis might then be more willing to sit back and let U.S. President Barack Obama try till the end of this year his policy of reining in the Iranian nuclear program by negotiations alone.
This year's election therefore may be the most significant in the history of the Islamic Republic, and its outcome will be closely scrutinized not just in the Middle East but around the world for its pointers to war and peace in the coming years.
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