This is a fun one: It appears John McCain has just given an interview in which he inadvertently revealed a key flaw in his attack on Barack Obama over Iran.

McCain has been hammering Obama for supposedly being willing to meet with Iranian president Mahmoud Ahmadinejad. Time magazine's Joe Klein yesterday grilled McCain about this, asking why he keeps bringing up Ahmadinejad, when the leader of Iran thought to control foreign policy is supreme leader Ali Khamenei.

McCain scoffed at this, saying that the president -- Ahmadinejad-- is the leader of Iran. But here's what McCain said today when he answered a foreign policy question in an interview with Essence magazine...

McCain: Absolutely. And President Roosevelt didn't sit across the table from Hitler and President Reagan didn't sit across from the Ayatollah Khomeini and President Kennedy didn't sit across the table from Fidel Castro. The president of Iran two days ago called Israel a stinking corpse. What are you going to talk about when you sit across from him? I don't believe Senator Obama has the experience and judgment. That is what will be the debate in this campaign.

During the 80s, Khomeini was the supreme leader of Iran. So back then, according to McCain, the leader of Iran -- the one a president would negotiate with, if he were so inclined -- was the supreme leader.

Now, suddenly, the president, not the supreme leader, is the leader of Iran -- because, conveniently, it allows McCain to link Obama to Ahmadinejad, the fellow spouting all the hateful rhetoric.

So which is it?

Not a huge deal, but a telling moment indeed.