Obama did, early in the campaign, say he would sit down at a presidential level with leaders of Iran and other "rogue states," without preconditions. But he did not mention Ahmadinejad by name and.

Further, as Biden pointed out tonight, Ahmadinejad is not necessarily the most powerful person in Iran.

Biden was also right in saying that US allies, particularly in Europe, have been urging the US to open a dialogue with Iran.