Signs of fraud abound, but not hard evidence

Millions of handwritten paper ballots were counted within hours. The challenger riding a surge of momentum and popular enthusiasm lost in a landslide. Other opposition candidates did poorly even in their home provinces.

Some analysts have suggested that the attention given the protests and anger in Tehran --where Western media outlets are concentrated -- gives a misleading picture of the Iranian electorate. The official results show that the leading challenger, former prime minister Mir Hossein Mousavi, was competitive in Tehran, losing by 52 percent to 46 percent, while trailing badly outside the capital. "You could get more of an impression of a horse race in Tehran," said Flynt Leverett of the New America Foundation, who said Ahmadinejad is a "really good campaigner" who blunted Mousavi's momentum in their final debate.

"There are suspicious elements here, but there's no solid evidence of fraud," said Walter R. Mebane Jr., a University of Michigan professor of political science and statistics and an expert on detecting electoral fraud.

Cautious reaction from U.S.

The Obama administration has reacted cautiously to the unfolding events, expressing concern about violence and "possible voting irregularities," but at the same time saying it wants to continue efforts to reach out to the government and restrain its nuclear ambitions. The ultimate power in Iran rests with its unelected supreme leader, Ayatollah Ali Khamenei, and U.S. officials have repeatedly said that he, not the president, is key to resolving the impasse over Iran's nuclear ambitions