At the age of five, he was smitten by John F Kennedy, then saw his hero reborn in the charismatic senator from Illinois. Now the presidential hopeful and his power broker are within sight of the ultimate goal - the White House

European leaders got their first glimpse last week of a remarkable Illinois political figure who has drawn strength from his complex personal history, ideals from the legacy of John F Kennedy and hope from an improbable campaign for the US presidency.

They also met Barack Obama, with whom this softly spoken former Chicago Tribune political reporter has forged a personal and political bond that even foes concede has been at the heart of the first serious bid by an African-American for the highest office in the land. His name is David Axelrod. And while US law forced a rare brief separation from his candidate during the opening part of last week's high-profile overseas visit - Obama's stops in Iraq and Afghanistan were as part of a government-funded Congressional mission - he was very much back at his side for its European leg in Berlin, Paris and London.

With his bushy moustache and piercing, no-nonsense gaze, the 53-year-old journalist turned political consultant has been a central presence in the presidential campaign. No one in the inner circle of Obama's aides has known the junior senator for Illinois longer; they first met during a voter-registration drive in Chicago in 1992, five years before Obama first won public office, in the state legislature. No one is closer to him. No one, except Obama himself, has had a make-or-break voice in every strategy decision during his march from outsider to front runner in the race for the White House.

For Axelrod, for reasons political, professional but also deeply personal, guiding Obama to victory in November has become more than just a challenge. It is, say those who know him best, a 'crusade'. And it began not with Obama's formal declaration of his candidacy in front of Illinois's capitol building on a cold February day 18 months ago, but nearly five decades earlier in Axelrod's boyhood home of New York.

The year was 1960. Axelrod was five, as he would recall the experience to fellow reporters when he began work on the Tribune. He had been taken by his sister to a campaign rally, where he heard the stirring oratory of another young senator who had set off on a journey to the White House: John F Kennedy.

'David was smitten, that's absolutely the right word,' says George de Lama, recently retired news editor of the Tribune, who began at the paper alongside Axelrod as a summer intern and became a friend. 'The experience of seeing Kennedy became etched in his memory - the excitement, the sense that something really important was happening.'

Eight years later, as a 13-year-old campaign volunteer, he sold lapel buttons and bumper stickers for the short-lived presidential bid of Robert, JFK's brother.

But if Axelrod's Kennedy-era sense of political idealism goes a long way to explaining his bond with Obama - and the course of the campaign, from its central message of 'change' to the echoes of JFK in last week's huge rally in Berlin - the focus and urgency he has brought to the fight has roots that are deeper and much more personal.

Axelrod was born in New York's Lower East Side and raised in Manhattan. His father was a psychologist, his mother a journalist for the city's crusading left-wing 1940s newspaper, PM. His early years no doubt helped to give him not only an interest in politics, but a sense that politics mattered.

But they also embedded other qualities remarked upon by friends and colleagues in the political word he has inhabited all his adult life: a sometimes moody introspectiveness. 'Soulfulness' is the word one friend uses; a seriousness; a 'driven' urge to succeed; and an 'inner toughness'.

When he was eight, his parents divorced. When he was 19 - a tragedy he mentioned publicly for the first time only in a moving Father's Day article for the Tribune - his father committed suicide. It began: 'My father died 31 years ago ...' and described him as my 'best friend and hero', an immigrant who had fled the anti-Jewish pogroms of eastern Europe, survived an 'unhappy, failed marriage', yet never showed any signs of sadness. It ended: 'It has taken me more than 30 years to say out loud that the man I most loved and admired took his own life.'

By then, Axelrod had moved west, studying political science at the University of Chicago and, first as an intern and, from 1977, a staff reporter, to the Tribune. He spent nearly eight years there, becoming City Hall bureau chief and then the paper's youngest political columnist, before leaving to join the campaign of another Illinois senator, Paul Simon.

Axelrod, says de Lama, was not only an incisive observer and reporter, but a 'beautiful writer - which you can see in some of the Obama speeches'. But when he left the paper, 'our editor said it was inevitable - that David loved being in the game more than writing about it'.

He founded a political consultancy and soon made his mark running the re-election campaign of Chicago's first African-American mayor, Harold Washington. He has since done work for clients ranging from the current mayor, Richard M Daley, to presidential hopefuls John Edwards and Hillary Clinton. But the Washington campaign proved a template for helping other African-American mayoral candidates, leading one commentator early in the Obama campaign to remark that Axelrod had 'developed something of a novel niche for a political consultant - helping black politicians convince white supporters to support them'.

Yet in Obama, almost from the moment they met, Axelrod seemed to sense something on a far grander scale: a potential for what he described to friends as a 'historic' agent for change in American politics on the scale of the hero he had seen as a five-year-old. He helped to run Obama's campaign for the US Senate in 2004 and was also credited with helping to craft the powerful Democratic convention speech in July 2004 that put him squarely on the national political stage.

'But long before then,' says Robert Shrum, the political consultant who ran the presidential campaigns of Al Gore and John Kerry, 'I remember David talking about Obama and what an extraordinary person he was.'

Before the presidential election season, with Obama's hat not yet in the ring, Axelrod told friends he was minded to take time off to produce documentary films. He had worked for two of the presumed front runners - Clinton and Edwards - and did not see how he could in good faith help one against the other.

But some friends suspect there may have been other factors at work. Axelrod married a Chicago University classmate, Susan Landau, while working at the Tribune - 'A wonderful woman,' says de Lama, 'who, I think David would say, has completed him, made him more of a thoughtful, caring person.' But their family life has not been without its own challenges. Their daughter Lauren suffered developmentally damaging epileptic seizures as a child and Susan also had breast cancer, from which she has now recovered.

'He wasn't going to work for any candidate,' says de Lama. 'But he did say that if Obama got into the race, he would make an exception. And I think the health problems of Lauren and Susan ... also gave him a real sense of urgency to make an impact, both in a lot of charity work he and Susan have done for epilepsy and now with the presidential campaign.'

Obama ran. And even the campaign's critics say its success has hinged on an unprecedentedly close bond between candidate and chief strategist, particularly as Clinton clawed back Obama's early lead in the primaries.

'Last September,' Shrum recalls, 'all the Obama fundraisers were in panic, saying Hillary's way ahead, we have to go negative on her, we have to begin running negative TV ads or attack her. And some were going after David, I think. Obama held a conference call and said look, we know what we're doing, we have a strategy and we're going to go ahead with that strategy and you all need to calm down.

'Obama seems to have that kind of quality - an equanimity, a serenity, vision - in almost all circumstances,' says Shrum. 'And David has it. They are melded in a lot of ways. And the fact that David can come over as low key should not disguise the fact that, intellectually, he is very, very high-wattage.'

To Axelrod's fury, there have been allegations that in its consultancy for business clients, his company has engaged in 'astroturfing' - PR campaigns that manufacture ostensible grassroots backing for their products. Even friends say his often sharp sense of humour can be 'offensive' to those he doesn't like or rate. De Lama says: 'David himself regrets, I think, a comment he made, on behalf of a campaign client, disparaging a rival senator as an "ageing hack in a reformer's body".'

But he adds: 'David's central strength is that he is a genuine idealist. His critics sometimes say that he falls in love with his clients, that he's a dreamer - something I think he would recognise.'

In Obama, friends are convinced, Axelrod sees a dream that may come true.

The Axelrod lowdown

Born 1955, into a middle-class Jewish family. His father was a psychologist and his mother a journalist.

Best of times (so far) 3 June 2008, when Barack Obama finally crossed the delegates' threshold to wrest the Democratic presidential nomination from Hillary Clinton.

Worst of times A policeman's knock on the door at his University of Chicago dormitory in May 1974 with the words: 'David, we just got a call from New York. The NYPD. They found your dad in his apartment. They think it was suicide. They need you to go home to identify his body.' After that, mere political knocks, even the recent threat that Obama's firebrand former pastor, the Rev Jeremiah Wright, might manage to derail his bid for the presidency, must seem trivial.

What he says

'I got into politics because I believe in idealism. Just to be part of this effort that seems to be rekindling the kind of idealism that I knew when I was a kid, it's a great thing to do... so I find myself getting very emotional about it.'

What others say

'He's not a Karl Rove [the Republicans' pugilistic political strategist] but in his own way he can be just as effective and just as tough. He doesn't back down from any fight.'

George de Lama, recently retired managing editor for news at the Chicago Tribune.