Sen. Jim Webb, D-Va., also a best-selling author, says he writes his own speeches and understands why Obama does so.
"When you live in the world of words, specific words are important," he says. "The impact of his words is so strong because they are so personal."
At the 2004 convention, as a state senator running for U.S. Senate, Obama told Democrats that America was not red states and blue states but "one people, all of us pledging allegiance to the stars and stripes." He was asked to remove a line that talked of "one America, red, white and blue" because a similar one was in Kerry's acceptance speech, says Bob Shrum, then Kerry's top adviser. Yet who recalls Kerry delivering that line?
Obama's impact as a speaker and the resonance of his calls to bridge divides are rooted largely in who he is: the son of a white woman from Kansas and a black man from Kenya, a man who grew up in Hawaii and Indonesia and has a half sister who is half-white, half-Indonesian. As Obama said in 2004 and many times since, "In no other country on earth is my story even possible."
Wayne Fields, author of Union of Words: A History of Presidential Eloquence, says Obama has a "special" voice fusing youth, artistry, a commitment to American values and "the complexity of the cultural change he represents."
Obama offers elegance, strong themes, "tremendous dignity" and relevance to the moment, says Clark Judge, once a speechwriter for Reagan.
However, "it's humorless," Judge says. "He doesn't make jokes. There's no sense of bounce there."
Should Obama lighten up? "I didn't say that. It works for him."
It's working, says Judge, because most people interpret Obama's more downbeat rhetoric as "we need a course correction." But some could hear it as an indictment of a "deeply fallen and deeply troubled society," he says, and that could wind up hurting Obama among voters.
Obama 'reeks hope'
Shrum, a veteran speechwriter, counters that Obama "embodies what Americans would like to believe is best about their country. His message is not a scolding message. It's a hopeful message. He reeks hope."
Rep. Rahm Emanuel, D-Ill., says the substance of Obama's speeches often is overlooked amid the focus on his stirring language and delivery, and shouldn't be.
"He is very good at analyzing a situation and making a concise and accessible argument," Emanuel says.
McCain is skewering Obama for his words and the huge crowds they attract. One TV ad shows Obama's speech last month at a park in Berlin, which drew an estimated 200,000, and scorns him as "the biggest celebrity in the world" but not "ready to lead."
In an ad dubbed The One, McCain's team uses Obama's words to mock him as a self-anointed messiah. The ad cuts from a pumped Obama on the night he clinched the nomination ("This was the moment when the rise of the oceans began to slow, and our planet began to heal") to Charlton Heston as Moses, booming, "Behold His mighty hand" as the Red Sea parts.
Fields calls put-downs of Obama's eloquence the refuge of those who aren't so eloquent. Their argument amounts to "you can trust our guy because … he's not eloquent enough to mislead you," he says.
For Clinton and now McCain, Obama's speeches have served as foils for them to portray themselves as straight-talking realists.
Democratic pollster Geoffrey Garin, Clinton's top strategist at the end of her campaign, now calls Obama's skills "an enormous asset."