Here are some of my thoughts on this matter. First, the main power in Iran rests with the Supreme Leader, Ayatollah Khameini, not the President. There is in fact enormous opposition to Ahmadinejad, as many of the people don't like him. The problem is that much of the opposition is driven by religious fundamentalism. There are no major pro-US political factions in Iran. The 99% in Iran? That's the percentage that hates the US.
Second, Iran is a threat to be create havoc with the global oil supply, but we can do more damage to them than they can do to us. There is only one petroleum refinery in the entire country, and one bombing raid would destroy their economy. Iran is not a military threat to the US.
Third, chaos is good business in Iran. As pointed out many times by the Village Elliot, every time Iran acts crazy, the global oil price increases. Right now they are in a giant pissing contest over nuclear inspections, and as a result, oil prices have gone up by about ten bucks per barrel. Iran exports some 2.5 million barrels per day, and so they are rewarded by 25 million dollars per day for acting crazy. The main problem is that this game needs to be played very well, and a miscalculation is very dangerous.
Fourth, weapons of mass destruction are real, and a Muslim nation with an eccentric government poses a real threat to the region, and to the rest of the world down the road. However, those weapons of mass destruction are owned by Pakistan, not Iran. So going to war in Iran does not solve that problem. So far, from what we are told in the media, Iran is carrying out enrichment studies on nuclear fuel, and they are deliberately obfuscating what they are doing. In the past, the US totally overestimated the capabilities of Saddam Hussein in Iraq, and now we are getting ready to do the same foolish thing in Iran.
This is not to say that the US should not respond if it has bona fide intelligence that a real threat exists, and at some point down the road, a future American President may be faced with the option of tolerating capabilities to create nuclear weapons by countries hostile to the US or removing those capabilities with a surgical air strike, as the Israelis did with the Osiris nuclear reactor facilty in Iraq some 30 years ago (the Israeli's, needless to say, had no illusions about taking over the country and rebuilding it to be a pro-Israeli state! They just blew it up and weathered the PR storm that ensued). But in Iran, that time is not now. The press has been filled with tales about Iranian nuclear capabilities, but in fact what they have done is to produce a fuel element for a nuclear reactor. Fuel elements are not nuclear bombs, and it is an enormous leap to be able to produce nuclear material for weapons. We have not been presented with any evidence that the Iranians are anywhere close to producing a weapon, and even if they were, that calls for a surgical airstrike rather than an occupying force.
There is no course of action which results in a stable pro-US, peaceful Iran. For the next several generations they are going to hate the US. There are no good ideas about what to do about Iran. However, going to war and taking over Iran would be the worst of all alternatives.
For additional Reading:
Iran: The garrison state conducts a parliamentary election , Al Jazeera, http://www.aljazeera.com/indepth/opinion/2012/02/20122208387572989.html
The CIA factbook, https://www.cia.gov/library/publications/the-world-factbook/rankorder/2176rank.html
