David Geffen is no dummy. When I called him today, he knew exactly what I wanted to talk about: "Maureen's column, right?" he said before I could finish a sentence. I guess you don't get to be a fabulously successful media mogul without having a sixth sense of what on someone's mind, whether they're a famous filmmaker or a tongue-tied reporter.

When historians start looking for turning points in the trajectory of the Obama campaign for the presidency, they will inevitably turn to Feb. 21, 2007, the day that the New York Times' Maureen Dowd ran a column where Geffen blasted then-Democratic presidential front-runner Hillary Clinton. He didn't just say he disliked Hillary, he dismissed her as "the easiest [candidate] to beat." He called Hillary overproduced and overscripted. "It's not a very big thing to say, 'I made a mistake' on the war, and typical of Hillary Clinton that she can't."

Geffen added that after eight years of George W. Bush as president, "I don't think that another incredibly polarizing figure, no matter how smart she is and no matter how ambitious she is--and God knows, is there anybody more ambitious than Hillary Clinton--can bring the country together." Geffen's indictment of Clinton caused a firestorm. It's easy to forget that back in the winter of 2007, Hillary wasn't just the front runner--she was considered inevitable. The entire Clinton campaign was based on a sense of her invincibility. Clinton operatives were telling deep-pocket party supporters--you better sign on now. The train is leaving the station and you don't want it leaving without you.

Geffen broke the spell. Having soured on the Clintons after raising huge sums of money for Bill and sleeping in the Lincoln bedroom--twice--Geffen found himself enamored of Obama from the first time he saw him on TV, giving a speech at the 2004 Democratic National Convention. "I thought he was a remarkable guy," Geffen told me today. "After I heard him give that speech, I called him up and said, 'You're going to run for president and I'm going to support you.' " Geffen says Obama laughed and said he was very flattered, but that he wasn't running.

Cut to two years later. "He called me one day and said with a laugh, ' David, I guess you're right. I am running for president and I'd like your support.' And of course, I said, 'You have it.' "

What is the private Obama like? And how did Dowd get Geffen to finally go public with his complaints about Hillary? Keep reading: