South Korean presidential elections tend to be tussles between well established career politicians, but December's poll has been enlivened by a candidate unlike any seen before in the country's 25 years of democracy.
Ahn Chul-soo, a 50-year-old technology entrepreneur and academic, is a stranger to the corridors of political power - but he has portrayed this as a virtue as he woos voters unhappy about social inequality and slowing economic growth.
"We need a fundamental remedy," he told business figures on Tuesday at a breakfast meeting of the Korean Chamber of Commerce and Industry. "If the ruling party and the opposition party co-operated, they could have solved so many problems. Politicians can't regain public trust if they don't change."
Mr Ahn's soft-spoken charm and clean-cut image helped him to develop a cult student following during three years as a university professor in Seoul, after he stepped back from the software company that he founded.
Many South Koreans - in particular the young - are disillusioned by infighting and corruption scandals in the political mainstream, and by a sense that the economic dice are loaded in favour of big business interests. Mr Ahn has responded with promises of stronger punishment for corrupt officials, a crackdown on anti-competitive practices by the powerful family-controlled conglomerates, and tax breaks for small businesses.
But on the campaign trail this week, Mr Ahn came in for tough questioning from interest groups outside his youthful core support base.
"Your plans to create jobs do not seem effective," said one chief executive at the chamber of commerce breakfast.
"Your plan to increase taxes [to boost welfare spending] is causing concern to companies," said another.
An hour later, having changed from a dark suit into a green fleece and orange zip-up cardigan, Mr Ahn arrived at a children's centre for a meeting with mothers who complained about the excessive pressure piled on children by the school system. "Politicians are too relaxed about the education problems," said Yang Eurn-hee, a member of the forum. They pretend to do something but . . . they just compromise so easily. I wonder if you can stand up for our children."
Seemingly unruffled by the tough questioning, Mr Ahn told the chamber of commerce of the need for a fairer business sector that would deliver greater innovation and a more prosperous middle class. To the mothers he promised an end to "the era of policy makers sitting at a desk", and the delivery of "an education system where children are the main concern for schools".
But the intense discussions reflect the high stakes in what is proving a closely fought race against two politically seasoned opponents. Park Geun-hye, the candidate of the ruling New Frontier party, is the daughter of the former military ruler Park Chung-hee and has spent most of her adult life in politics. Moon Jae-in, the nominee of the centre-left Democratic United party, served as the president's chief of staff in the last liberal administration.
By contrast, Mr Ahn has almost no political experience. After a middle-class upbringing, he trained and worked as a doctor before developing an interest in computer science. In 1995 he founded Ahnlab, which went on to become South Korea's biggest antivirus software provider. Having made his fortune, Mr Ahn stepped back from the company in 2005 - while maintaining a large stake - and studied management in the US before his stint in academia.
Speculation last year that Mr Ahn would run for the mayoralty of Seoul shocked political insiders who consider him dangerously unqualified for high office, and his entry to the presidential race has sparked fierce opposition from career politicians. "He has held no public post whatsoever," says Lee Hye-hoon, a member of the New Frontier party's supreme council. "He is like a novice driver. It is very risky to let someone like him run the country."
Moreover, the absence of a party support base would render Mr Ahn "impotent" in his dealings with parliament, says Kim Ki-jung, a professor at Yonsei University who is close to Mr Moon.
But it is precisely this lack of political pedigree that is energising Mr Ahn's core supporters.
"Many say that Ahn's lack of political experience is worrisome, but I think that is actually an asset to him, not a risk," says Jung Goo-hoon, an unemployed 26-year-old. "Party-backed politicians care about the party and the members' interests, but Ahn doesn't have to. The problems in Korean politics come from the experienced politicians."
Yet speculation is mounting that Mr Ahn will have to enter the party political fold if he is to be elected. On Tuesday, Mr Moon urged him to enter talks that would see one of them quitting the race, to avoid splitting the liberal vote.
Lee Hae-chan, chairman of the opposition DUP, says that Mr Ahn would be welcomed as the party's candidate if Mr Moon gave his blessing. "I believe the DUP members and supporters give greater priority to a change of power than to who becomes our candidate," he says. "Ahn Chul-soo cannot run the country as an individual."
Additional reporting by Laeticia Ock in Seoul