The United Front for Democracy Against Dictatorship, the political pressure group most 'red shirts' are members of, make up a grass-roots mass movement initially created to engineer the return of tycoon-turned-populist-politician Thaksin Shinawatra, ousted in a 2006 bloodless military coup.

By almost any measure Thaksin is a member of the elite, yet slick marketing and the deployment of populist handouts transformed him into a people's hero who easily won three elections between 2000 and 2006. Despite being convicted of corruption in 2008, Thaksin has a loyal following in rural areas and still moves many to tears with his generosity and goodwill.

'Thaksin stunned [the establishment] by shockingly promoting policies like cheap loans and health care that actually helped poor people. But we are now way, way beyond Thaksin - this is about creating a state that helps all people, not just the privileged,' UDD leader Jaran Ditthapichai said.

One 'red shirt' strategist said a massive unarmed protest, by flooding symbolic corners of the city, would help break open a 'closed political regime'. A similar tactic used in post-Soviet Eastern Europe, which signalled a era of change and possibility, and encouraged the vested powers to negotiate.

The 'red shirts' include many dubious characters and paid political hacks, but at its core are activists committed to 'freeing' a society they see as encrusted and trapped by a self-serving coalition of reactionary soldiers, complacent bureaucrats, royal toadies and craven politicians.

These activists calculate that their sheer weight of numbers will fatally undermine a government allegedly foisted into power only after several ranks of more popular politicians were banned by 'political courts' for infringing election laws.

Without a popular uprising the 'red shirts' believe an allegedly reactionary military will prevent Thaksin's proxy political party, Pheu Thai, from winning any future election.

Yet some in the 'red shirt' camp say the attempt to thrust a political dagger into the heart of the Thai state is a mistake: that it would be better to consolidate the movement's impressive political infrastructure, fashion an alluring manifesto and prepare to fight a national election that must be held before the end of next year.

'Why rush? We have the best arguments and the best ideas. Why risk alienating many of our potential supporters when we can wait a few more months,' one intellectual close to the 'red shirt' leadership said. (No senior activist will publicly criticise Thaksin.)

The answer that even many senior 'red shirts' suspect is that Thaksin wants quick elections and a personal pardon to overturn a jail sentence for corruption in office and to see the return of US$1.4 billion seized by the courts.

'Thaksin represents hope for many ordinary Thais ... But he is a tricky friend,' an intellectual sympathiser said.

Thaksin is seen even by many as too tainted, vindictive and loathed to ever strut the Thai political stage again, even if his charismatic two-dimensional presence remains useful to the 'red shirts' for now.

Hard-core 'red shirt' supporters are likely to brush off Thaksin's troubles as a result of political machinations by a biased establishment. And now, they are ready to put on a noisy and photogenic show this weekend.

Gothom Arya, director of Mahidol University's peace study centre and a prominent voice of moderation, said: 'The 'red shirts' are tied tight to Thaksin who was a trigger for protests over injustice and he could [still] be a unifying force, but they might also risk being on a sinking boat. It's a very complex situation.'