David Axelrod can clearly remember where he was the first time he saw the man who inspired him to believe that politics can change the world. The strategist behind Senator Obama’s White House campaign was perched on a post box in New York City as he watched a Democrat with a silver tongue fire up a generation of young voters.

The twist is that Mr. Axelrod was then just five years old and the candidate in question was John F. Kennedy. But it is not fanciful to suggest that what he saw that day has shaped his life ever since.

By the age of nine, Mr. Axelrod was handing out leaflets for the New York Senate campaign of Bobby Kennedy, the man to whom Mr. Obama is most often compared by dewy-eyed American liberals.

There is an episode of the “West Wing,” the drama, where Leo McGarry, the grizzled chief of staff, tells his deputy, Josh Lyman, that every political strategist has just one truly special candidate in their career. His was Jed Bartlett, the fictional president.

And so it was that Mr. Axelrod, a man who has worked on five losing presidential campaigns, found his Bartlett in 1992, when he was introduced to a young African American activist who had impressed Chicago’s “latte liberals” on a black voter registration drive.

Messrs. Axelrod and Obama immediately hit it off and have developed a close personal bond reminiscent of that between Prime Minister Blair and Alistair Campbell, based on progressive causes, late night games of basketball, and a mutual love of the Chicago White Sox baseball team.

Mr. Obama consulted Mr. Axelrod before he made the anti-war speech in 2002 that first made his name, and again when he was writing his autobiography, “The Audacity of Hope.” Mr. Axelrod made adverts for Mr. Obama’s successful senate run in 2004.

Now, he is the architect of the Mr. Obama campaign for the presidency — constantly honing the message, studying polling figures and working out his candidate’s next move.

“I thought that if I could help Barack Obama get to Washington,” Mr. Axelrod said, then I would have accomplished something great in my life.”

With his lugubrious moustache and doleful eyes, Mr. Axelrod’s demeanour is not that of a man on the cusp of making history if Mr. Obama wins this November. But his ear for language and his calm in the campaign hothouse have made him Mr. Obama’s closest aide, the “keeper of the message” who first decided “Change” would echo through this campaign.

Mr. Axelrod claims no credit for the rhetorical flourishes. “One thing I came to realize early in the process of working with Barack was, he was always going to be the best writer in the room,” he says.

But he was smart enough to build a campaign organization that would underpin the soaring speeches. He brought in business partner David Plouffe to run the nuts and bolts of the ground war, a move that ensured Mr. Obama’s inner circle pulled together during the primary elections while Senator Clinton’s aides formed a circular firing squad.

Mr. Axelrod borrowed from and improved the Internet campaigning of his friend Joe Trippi, who masterminded Howard Dean’s “netroots” campaign for the 2004 Democratic nomination, combining it with the kind of community activism on which Obama cut his political teeth.

A Democratic strategist, Steve McMahon, said: “David Axelrod and David Plouffe have run maybe the best campaign in my lifetime. Beating the Clintons wasn’t easy and they did it.”

When he joins Obama at his major events, he is also one of the most approachable people in politics on either side of the Atlantic, just as happy to shoot the breeze with foreign reporters and the Armpitville Gazette as the dandies of network television news.

This approach was hugely beneficial to Mr. Obama during the primaries, a contrast with the hate-hate relationship between the Clinton media machine and the press corps.