For more than two months, Suthep Thaugsuban has directed a successful people's protest. He has shown the country a powerful opposition, forced the government to resign and put much-needed political reform on the front burner.
But his plan to "shut down Bangkok" next week is a step too far. It puts his great mass uprising on a dangerous trail that risks fringe violence, harms ordinary people and once again punctures the country's image.
The tactic is a sign that Mr Suthep's movement has lost focus. In fact, he has the government and the country exactly where he said he wanted them when the campaign began in November. It is actually the right time to stop, take stock and move to the only acceptable next stage _ negotiations over exactly when to start political reform, and precisely how to proceed.
Mr Suthep seems to be carried away with his own success, but can see only one side of his campaign. The whistle-blowing muan maha prachachon (mass uprising) has seemingly gone from strength to strength on the streets.
But this is not exactly true. For example, Mr Suthep has falsely promised "total victory" on several occasions. The thousands of faces watching his nightly speeches exclude roughly equal numbers of Bangkokians who do not approve of either his goals or his methods.
This did not matter until now. He and the entire mass uprising were properly and legally using their guaranteed rights to assemble and speak freely. There are those who have been inconvenienced, but they are a small percentage. The campaign to be previewed this week and put into effect next Monday, however, is more than just a major escalation. It puts the protests on an entirely new plain. If Mr Suthep actually implements his blockade of inner Bangkok next week, it will be illegal, dangerous and actually harmful to millions _ a vast majority of his fellow citizens.
It is illegal under many laws, as it will block traffic and interfere with business. Mr Suthep has actually promised to assault and threaten any Thai who tries to move across his barricades, on public streets and pavements. Although Mr Suthep said on Saturday that the rallies would be limited to main intersections and state agencies, the country's two largest business groups _ the Federation of Thai Industries (FTI) and the Thai Chamber of Commerce _ point out that apart from closing tens of thousands of businesses, Mr Suthep's plans are likely to shut oil outlets and impede the supply of medicines and emergency supplies to hospitals.
This is long before the effect on tourists and the resulting demolition of the country's image overseas.
Two such recent ill-considered protests ended badly. In 2008, the yellow shirts' protests resulted in an orgy of murders and the closure of Bangkok's two airports. In 2010, the red shirts moved against inner Bangkok, bringing about the deaths of another 92 Thais and sparking another binge of arson, assaults and attacks.
Mr Suthep, who was personally and deeply involved in that 2010 violence, had no plan then and has no plan today to prevent or even to minimise the predictable attempt by third hands or fringe supporters and opponents to prevail or punish with murderous results.
As His Majesty the King pointed out so correctly and concisely in his New Year's message, all Thais have the same desires _ happiness, prosperity and a peaceful country. Virtually every citizen has the same goal for the nation. There are only minor differences on which road can get us there. Mr Suthep should help to solve those differences, rather than begin a new, almost certainly destructive, campaign to avoid success.