If Obama was nervous, he kept it hidden. In fact, he played nine holes of golf the next morning, before returning to the White House to monitor the unfolding mission during what he later described as "the longest 40 minutes of my life."

It was retired Air Force Chief of Staff Tony McPeak, an Obama supporter, who first called him "No-Drama Obama" during the 2008 campaign. The nickname stuck, perhaps because sang-froid is central to Obama's personality.

"That measured approach to everything characterizes a lot of what he has done," says David M. Kennedy, Pulitzer Prize-winning historian. "It's kind of remarkable how he has stayed in character, as if he were the calm, cool grown-up in the room."

This has not always worked in his favor; at his first debate with Mitt Romney, he appeared detached, almost professorial, and he took a beating in the polls. Repeatedly, he has frustrated supporters who say he does not express righteous anger when he should.

Kennedy recalls that in 1936, when FDR was running for his second term, he declared the start of the second New Deal — and pronounced himself ready to take on the many, moneyed powers aligned against him: "They are unanimous in their hate for me — and I welcome their hatred."

Obama, Kennedy says, is "temperamentally incapable" of taking that kind of stand. "It's just not in his bloodstream."

Not that everyone believes the Obama story.