My two cents:
Both candidates are revanchist--in the sense that the Islamic Republic of Iran's Constitution itself is revanchist, meaning a "political policy, as of a nation or an ethnic group, intended to regain lost territory or standing." The Constitution is explicitly anti-colonialist, calling for self-reliance and attempting to ensure an absence of outside interference.
All candidates for the Presidency must be vetted by the Guardian Council. Half of the members of the Guardian Council itself are directly appointed by the Leader of the Revolution [LOTR], half are chosen by the Chief of the Judiciary (different from the Minister of Justice) who himself was appointed by the LOTR and confirmed by the Majlis (Iranian Parliament), candidacy for which is also approved by the Guardian Council. (For a long piece on Iran's Constitution, and why reformers see it as a potential means of providing for human rights in Iran, contra the establishment, see Law and Revolution in Iran.)
Iranian politics thus do not fit the mold of left versus right as in the West, or even really reformist versus conservative. There is the establishment, and then there is the slightly less establishment.
What Ahmadinejad is is a populist anti-establishmentarian--he is taking on the old guard of the Revolution. He has replaced senior officials in all branches of the Executive with his own guys--the people he replaced mostly got their jobs due to political connections with the Old Guard. One of his most radical moves was to completely replace the senior diplomatic staff of the government. His constant refrain is to argue against the "corruption" of the old Guard--indeed, the recent kerfuffle with Rafsanjani--see Daily Sources 6/10 #8--is mostly about his accusation that Mousavi is backed by the "corrupt" elements of the old Guard, personified by the "puppet master," Rafsanjani. He's a caudillo wanna-be, greatly limited by the Constitution's emphasis on the LOTR and various institutions designed to guarantee the Islamic nature of the government.
Mousavi is the old guard, a previous prime minister, tied in with the Revolutionary Guard, the bonyad system†, and backed by Rafsanjani--he is the establishment choice, which is why he might be the first presidential candidate to unseat the incumbent in the history of Iranian presidential elections.
Thus, it might be somewhat ironic that some in the West appear to be excited about Mousavi, when Ahmadinejad, awful and obnoxious as he is, is the candidate who threatens to overturn part of the power structure there. Mousavi will likely make less anti-Semitic comments in the press, seem more reasonable, return the Old Guard's picks to their places in government, and, as such, be resolutely less populist than Ahmadinejad--as Ahmadinejad's views, though horrific, do have currency throughout much of the Middle East.
Thus, strange as it is to say, Ahmadinejad is the candidate of change, though much of that change would be expressed in ways that we are uncomfortable with. But it is change that could weaken the existing power structure. If he were able to grab more power, he would certainly continue to make efforts to undermine the existing power structure, unlike Mousavi--and likely make the Iranian system weaker and more malleable in the future.
(Of course, enthusiasm in the West for Mousavi might undermine his candidacy, because it could be interpreted as a sign that he the West's choice, and potential tool.)
Iranic ... if you will ... ain't it?
† One key element of the Old Guard is the "bonyad system"--charitable trusts which represent as much as 20% of Iranian non-petroleum GDP, and which are all directly answerable to the LOTR.
Juan Cole at Informed Comment notes that some neo-cons are openly rooting for a Ahmadinejad win. I just want to make it plain that though I think that Ahmadinejad would do more to weaken the regime than Mousavi, I do not truck with the neocons.
Cole also links to an interesting and detailed analysis by Walter Posch via the Middle East Institute.
Gary Sick--one of our country's most insightful Iran analysts--notes that Rafsanjani's letter is unprecedented and asks if the LOTR, and the rest of the establishment has found that it has lost control of events on the ground:
"Thus far, Khamene`i has remained utterly silent in the face of Rafsanjani’s direct challenge to him to act or else risk the future of the Islamic system. Whatever Khamene`i decides to do – facilitate a possibly unfair election of Ahmadinejad, encourage the more liberal opposition, or simply do nothing – he is at risk of being unveiled as quite an ordinary man whose powers are anything but magical and who has no answers to the tumultuous uncertainties generated by an election that is assuming historic importance.Al Jazeera reports that the head of the Revolutionary Guards has reacted to the large number of people on the street by issuing a statment warning that a velvet/color revolution will be put down:
No one in Iran appears to be fully in control of events that have a potential to mark a turning point in the history of the Islamic revolution."
"'There are many indications that some extremist [reformist] groups, have designed a colorful revolution ... using a specific color for the first time in an election,' the statement said.The text of Rafsanjani's open letter to the LOTR via TehranBureau.
Calling that a 'sign of kicking off a velvet revolution project in the presidential elections', Javani vowed that any 'attempt for velvet revolution will be nipped in the bud'."
Shirin Ebadi's op ed in the Washington Post where she says:
"I am often asked about the elections, but what I think about who should win doesn't really matter. As a lawyer and as someone who has spent my career fighting for and within the Iranian legal system, I am more concerned with the legality of the protection of human rights within Iran. The true mark of success in Iran will be an election that follows due process. Politicians come and go -- but a healthy, functioning and fair legal system is the people's long-term guarantee for greater human rights. "