George Weah turned 39 10 days ago. It was a lovely day. He got up late as usual, but instead of celebrating at home with his family, the former footballerwoke up in Zwedru, a godforsaken place in the middle of nowhere near the border with Ivory Coast and at least two days' drive from the Liberian capital, Monrovia.

Today, Weah will play the most important game of his life: it is the presidential election of Liberia, in which he is a candidate. But the closer election day has drawn, the more sullen Weah has become. He has shut himself away with his closest aides for endless meetings, shunning the press, who are hounding him with the same question: How can a footballer lead a country?

The campaign has been running behind schedule, and the rainy season has turned the slightest journey into an obstacle course. Candidate Weah travelled in a convoy of about 50 vehicles which is impossible not to notice. They included his closest aides, his old Rastafarian friends, his young supporters, his chefs, his bodyguards, his hangers-on, and prostitutes...

George Weah is like a tropical cyclone, raging through a state already devastated by 14 years of civil war. His appearances provoked hysteria and shook the political establishment. Ever since becoming the favourite, he has been the target of rumours and death threats. Weah is the candidate to beat, if not kill.

But Saturday was his birthday, and Weah was in a good mood. He had decided to visit Tuzon, the birthplace of the former president Samuel K Doe, which is six miles north of Zwedru. Doe was like a father to Weah, say young Liberians - his "papay" - and his benefactor. In 1980 Doe, a 28-year-old army sergeant, seized power by assassinating President Tolbert, becoming the first indigenous leader in a country monopolised, since its independence, by former Afro-American slaves who returned to Africa after being freed from bondage.

George Weah was 13 years old at the time of the "revolution". Before becoming a bloody dictator from 1985, Samuel Doe had embodied the hopes of the 90 per cent of Liberians who were living in misery. Just like Weah, who was brought up in a shanty town called Klaratown by his grandmother after his parents separated. Because he adored football, Doe took an interest in Weah's career early on. The President even sent the best footballers to train in Brazil at a cost of $100,000, to the annoyance of Liberians who found the price tag a bit steep.

As it pulled into Tuzon, Weah's huge Hummer lumbered over a little wooden bridge before driving past the remains of Samuel Doe's old residence: only the frame is still standing. A blue plastic tent had been erected to receive the presidential candidate and the whole village had turned out: kids in tattered clothes, women in tops, village elders in traditional boubous. Weah, dressed in jeans and trainers, looked on in silent amusement at the welcoming ceremonies. He chewed on a cola nut, allowed his face to be daubed with flour, and listened to the welcome songs.

Edith, the sister of Samuel Doe, came to the microphone. "We will never forget that you have come to see us. Even during the war, in 1990, while we were besieged in Monrovia, with nothing to eat, you sent us humanitarian aid. Rest assured that we will vote for you."

In 1990, Samuel Doe was toppled by rebels led by Charles Taylor, and executed by Prince Johnson, a rebel army lieutenant. Tuzon was ravaged by Taylor's army and its inhabitants fled to Ivory Coast.

Weah listened like a sphinx, concentrating behind his glasses. Then came his speech: "I have come to ask you my friends the Krahns to promise me that you will make peace with all the other groups of Liberia. We must have a non-violent revolution. The whole world thinks we will plunge back into war. We must show them that we are ready for unity and peace." In each sentence, he repeated peace, peace, peace. "Brotha George", as he is known, moved around chanting like an evangelical preacher and left his audience in a trance.

Liberia, which is proud to be the first independent country in the history of modern Africa (1822), has often served as the laboratory of sub-Saharan Africa, often for the worse. Apartheid and one-party dictatorship marked the long reign of the American-Liberians. Then, after 1990, came contemporary African warfare - tribal, savage, privatised, spectacular and absurd. So will Liberia be the first country in the world to elect a footballer as president?

In the last vote in 1997, Liberians chose Charles Taylor, whose young supporters campaigned by shouting: "He has killed my mother, he has killed my father, but I vote for him." The other slogan was, "No Taylor, no peace!" But once in power, Taylor did not end the war. As the leader of his wild-eyed child-soldier Small Boys Unit who, drugged up to the eyeballs, terrorised the civilian population, Charles Taylor was the prototype warlord - part politician, part general, part mafia don - who trafficked diamonds and timber. Paradoxically, Weah is now popular with the same young "ex-fighters" who noisily accompany him wherever he goes.

With his bandanna wrapped around his head, 19-year-old Joshua dropped everything to follow his candidate. In fact, he has no family and no "Papay", since Charles Taylor, under intense international pressure and under attack from two rebel movements, was forced to quit power for exile in Nigeria in August 2003. Joshua returned his weapons to the UN for $300 and now survives on small-time drug deals and petty crime. For him, Weah is "a chief", whose weapons are the football, money and celebrity, rather than a Kalashnikov.

The former player for Chelsea and Paris Saint-Germain is often criticised for his popularity, encompassing people from all walks of life. "Yes, we rehabilitate child soldiers, prostitutes and down-and-outs, but Weah is the only one who will take them under his wing," says Geraldine Doe-Sherif, a portly 35-year-old woman nicknamed Zico since she captained the first women's football team of Liberia in the late 1980s. She is co-ordinating her idol's campaign despite having four children to look after and a job with the national oil company. "The Messiah didn't come for perfect people, but for fishermen."

Back in Zwedru, Weah was making a more political speech to 2,000 crammed into the village hall.

"The other candidates criticise me for having no education. Yes, I'm only a footballer, but I have used my success and my professionalism to help you. They are covered in degrees, but they have destroyed your lives. What have they done with our country's money? There are no roads, no schools, no hospitals, no electricity and no running water ... They sent your children to refugee camps that they never even bothered to visit. I am like you; I know what it's like to be hungry, or to go to school barefoot. Things must change, take your destiny in your own hands!"

The crowd exploded with joy. Weah, aware of his own youth and inexperience, has used this as his primary campaign argument in a country where almost every politician has been implicated in murder and pillage and where 60 per cent of the population are under 30. Weah always kept in touch with his native country during his international career, financing humanitarian aid programmes, accepting the role of goodwill ambassador with Unicef, and supporting the child soldier disarmament programme. He has embodied another Liberia, one without war, firstly by the hat-trick of becoming world, African and European footballer of the year in 1995, then by only just failing to qualify his country in the 2002 World Cup. In his national team, he held every position, as captain, coach and president of the federation: he bankrolled the other players' air fares and bonuses.

Such popularity soon earned him Charles Taylor as an enemy. In 1996, when Weah called for UN troops to be sent to his country, Taylor sent his militia to burn down Weah's house in Monrovia and rape two of his cousins. Fearing for his life, Weah did not set foot in Liberia again from 2002 until its president went into exile.

The return of peace, guaranteed by 15,000 "blue helmets", encouraged Weah to announce his candidacy a year ago. His return was celebrated by thousands of Liberians.

In Monrovia, Weah is king. He owns a radio station, King FM, and a television channel, Clar TV, named after his American wife of Jamaican origin, who preferred to stay at home with their three children in Florida during campaigning. When Weah drives around the pot-holed streets of Monrovia in his Porsche Boxster, there's a riot. And when he stays in, crowds of poor people mill around his house or the offices of Congress for Democratic Change - more a fan club than a political party.

Since the campaign began in August, Weah has become the target of the 21 other candidates. They tried to invalidate his candidacy on the ground that Weah took French nationality 10 years ago. Those who offered him the position of Vice-President on their ticket now cast doubt on his intellectual ability. Others say that you can't trust a man who converted to Islam and then became a Christian again. The pressure has been enormous but Weah has always had political reflexes. "He always leaves the door open for negotiation," says Gilles Verdez, a journalist with Le Parisien who followed his years in France. "And he relies a lot on his team. That's his strength, but it could be his weakness if he chooses badly."

His staff are a motley collection of opportunists, technocrats from America and politicians. Embarrassingly, the first chairman of his party, Orishall Gould, was forced to resign for embezzling social security funds he administered. His press officer, Margot Cooper, was charging media for interviews before she was sidelined. And three of his bodyguards are reported to have belonged to Taylor's notorious Anti-Terrorist Unit.

Now all that remains to be seen is whether he has realised to what extent winning the presidential election is not the end of the contest, but only the qualifying round.