With high oil prices and shockwaves from the subprime mortgage crisis roiling the global economy, Mr Lee has been unable to deliver economically - particularly as he promised 7 per cent annual growth, well beyond the 4.9 per cent figures of his predecessor, Roh Moo-hyun.

Moreover, his cabinet appointments sparked anger for being representative only of society's elite. Others have criticised his top-down 'CEO management' - he was a former chief executive of Hyundai Construction.

Formerly known as 'the bulldozer' for his dynamic and uncompromising leadership style, he now has a new nickname: '2MB' - a reference to his name (which means 'two' in Korean) and initials. In a nation known for high-speed broadband connections and world-leading mobile phone technologies, 2MB is derisively clunky.

But in ultranationalist South Korea, it took a foreign issue - US beef imports - to ignite protests. Now, Mr Lee is facing hundreds of thousands of demonstrators who have moved from calling for the halting of imminent imports of beef to demanding his head.

Mr Lee, on his first trip to Washington in April, announced a beef deal with President George W. Bush. Beef imports are a critical issue as US congressmen refused to ratify last year's Korea-US free-trade agreement unless Seoul readmits beef. Korea was the No3 market for US beef but halted all imports due to mad cow scares in 2003.

The trade agreement is central to Mr Lee's policy of economic revitalisation and a better relationship with the US, meaning he had to resolve it, but the manner of his doing so - a surprise announcement following closed-door meetings - shocked the public.

In the wake of a television documentary that alleged South Koreans are more susceptible to mad cow disease than Americans or Europeans - an allegation that has since proven unfounded - rumours exploded across the internet, leading to many Koreans becoming convinced that US beef will cause a mad cow disease epidemic.

Meanwhile, a bird flu epidemic that resulted in the culling of 7 million birds nationwide was largely ignored by the public.

The US Centres for Disease Control claims no one has ever contracted the human form of the affliction from American beef. US Commerce Secretary Carlos Gutierrez, on a visit to South Korea last month, made clear that the beef to be exported is the same as that fed to Americans. None of this appeased Koreans.

Last week, the US ambassador to Seoul, Alexander Vershbow, suggested Koreans look at the science and facts. He was immediately lambasted by opposition politicians who said his comments were patronising.

During weeks of protests, demonstrators have held aloft candles, echoing nationwide protests following the death of two girls in a traffic accident with US troops in 2002. But the government stood firm, saying beef renegotiations were not possible. But Mr Lee this week caved in and sent his top trade negotiator to Washington to renegotiate the inflammatory beef deal.

Kim Jong-hoon, who negotiated the trade deal, hopes to win concessions from Washington, such as an agreement that meat from cattle over 30 months will not be exported and the right for Korean officials to examine US meat-exporting plants. He may face a hostile reception as US officials have called on Korea to stick to its agreements.

'This issue is not a vacuum, it is wonderful fodder for the anti-trade agreement people in the US,' said a source in Seoul. 'They are foaming at the mouth. They are saying, 'You can't trust the Koreans, they don't stick to their agreements'.'

In downtown Seoul, anti-US beef banners and spray-painted graffiti on road intersections demanding the resignation of the president were still visible 36 hours after more than 100,000 people flooded the capital on Tuesday night. Despite a heavy police presence and the unprecedented construction of giant barricades using shipping containers - dubbed 'Lee Myung-bak Castles' by protesters - demonstrations have been largely peaceful.

Given the apparent lack of focus and leadership in the protests, and their diverse participants, analysts say much of the passion stems from Koreans' penchant for group experience, originating not just in the pro-democracy protests of 1987 but also in the carnival-like street atmosphere of the 2002 Soccer World Cup. Even so, some are concerned that the spectre of anti-Americanism is rising.

'President Bush visits Korea in July,' said Hahm Sung-deuk, a professor at Korea University. 'If this problem is not resolved, it will become anti-Americanism. The Bush administration has to help Lee and allow him to renegotiate the deal.'

Other pundits question whether the Korean public - ultrasensitive to political issues, ideologically divided and distrustful of its politicians - is losing its faith in the democratic processes for which it fought so hard in the 1980s.

Although Mr Lee won a record majority in December, voter turnout was the second lowest ever.

'The positive point is that these demonstrations are 'do it yourself' politics: They feel the government cannot do it, so people are trying to make it themselves,' said Lim Jie-hyun, a nationalism expert at Hanyang University.

'But I am worried that this kind of demonstration violates basic principles of democracy: There is no democratic process in 'DIY politics'.'

With a legion of civic groups and political idealogues permanently ready to pounce, and in a heated atmosphere of confrontational politics and street theatre, it seems as if any sensitive issue that has the power to inflame public sentiment has become a political no-go area, paralysing governance.

'There is a popular disappointment with the new president, and I suspect that of the people out there, some have a clear political agenda while others did not bother to vote and now are suddenly fired up with a cause,' said Mike Breen, author of The Koreans. 'They have a shallow idea of the social contract of democracy.'

The spectacle of a 'lame duck' president is not a new one.

Right-wing politicians sparked a political crisis by unsuccessfully attempting to impeach Mr Roh early in his term. Although the former president overcame that crisis, he constantly complained that a negative press and public made it impossible for him to govern effectively.

In fact, Mr Roh agreed to re-import US beef once it achieved international approval from the World Organisation for Animal Health - which it did last year - but he never did, apparently for fear of public censure.