I don't have an opinion on who should win the election. I don't think one hard-liner is much better than another. I do, however, feel for the people who think the election was stolen from them. As an American, I felt the same in 2000 and 2004. Unfortunately, my concerns about those elections were never addressed (although more proof that fraud happened surfaces every day). It appears the same will happen in Iran. The only question now is how the people of Iran will react to the election fraud.
I wish them well, but this is entirely an internal Iranian problem. Anything the US government can say will only make the situation worse. Obama's choice to leave the whole thing alone is certainly the best choice at the moment. He can criticize the violent reaction to the protests, but he cannot take sides.
The Republicans who are criticizing the President's decision to leave it alone are idiots. But then, most of the current Republicans in office are idiots.