One of the current right-wing talking points on this seems to be that "if the saviour (their word for Obama) doesn't declare his support for these freedom fighters now, then he will be complicit in their downfall."
Like most right-wing screed these days, this is specious and stupid. Of course, some of the reasons for that have to do with the extensive and draining elected war in Iraq from which we are slowly withdrawing our troops.
First, you may have noticed a distinct lack of American flags or pictures of Obama or signs bearing his name in that vast crowd. Iranians do not want our interference. Even among the more progressive sectors in their politics, feelings about the west and its presence in the middle east are ambiguous at best. If Obama were to come down on any side in this moment, it would have very unpredictable consequences as the side he chooses will scramble to distance itself from the west and the opposition will draw support from the center. If he picks the Greens, he would lessen their domestic support and any support that they're receiving (or might receive) from their neighbors.
Second, let's imagine that Obama comes out in support of the the Greens. Now let's imagine that the ruling factions determine that the vote count stands (after whatever sham investigation they conduct). That leaves Obama with two options, neither attractive, and both worse for the United States.
A) He does nothing, and has created a remarkably weaker hand for himself with Ahmadinejad and his government, who can credibly claim that the US intruded into domestic Iranian politics. He can pretty much do what he wants after that, and the US will have to scramble to regain any credibility in the area.
B) His declared support for the Greens may bind him to act if it is determined that they will be shut down by the Mullahs. But act with what? Our forces are already over-deployed in Iraq and Afghanistan. Of course, the American right wing has never shied from an opportunity to kill massive amounts of brown people through "smart" bombing, so maybe this is just what they want. In any case, he becomes practically bound to some course that will lead to violence.
Finally, judging the majority will of Iran by what happens in the city of Tehran is a little like judging what people are thinking in Oklahoma City by what they're saying in San Francisco. Thanks to our near-complete lack of presence in Iran, we have nearly no idea what the "man in the street" in that country is thinking. Our government is relying on the same "free" intelligence that we all are -- largely, the British press.
But the American right-wing wants Obama to back the Greens now and without reservation. I wonder where they were when Saddam was gassing the Kurds? Or when Clinton wanted troops on the ground to protect Muslims in Kosovo? This fake litmus test betrays both a simplistic analysis of the situation and a hypocritical approach to international policy.
In other words, utterly predictable.
That said, this is already turning violent. If the general stability of Iran is at stake, the smart move for Obama, in my mind, is to pull a Poppy Bush. That is, begin working through Syria to build a regional coalition to moderate the situation with US support from over-the-horizon. It won't be the show the Right so deeply desires, but it would have the potential to do two things: it would enlist the regional neighborhood of nations in maintaining stability in the one place they need to maintain it if they hope to avoid a Balkan catastrophe, and it would establish the US as an honest broker with governments that should be partners (if not allies) with us in the region. It might even provide an opportunity to engage Turkey in a more influential role in the Persian states, something that could be very useful down the road.