A convoy of indigenous rebels led by a charismatic former philosophy professor is rattling its way towards Mexico City this week, filling public squares and worrying Mexico's political parties.
The Zapatista National Liberation Army (EZLN) declared war on the Mexican government in January 1994, demanding land and autonomy for Mexico's 11 million indigenous people, an estimated 10 per cent of the country's population.
The masked but unarmed rebels will address the nation's parliament next week to pressure for the approval of an Indian rights accord, signed in 1996 but never implemented.
Two dozen rebel commanders left their Lacandon jungle base in south-east Mexico last week, risking their lives to bring their message to the nation. The popular reaction has exceeded all expectations, as schools shut down to allow pupils wave at the convoy. Public events have the air of a rock concert, as thousands of youths jostle for a closer view of the rebel leadership.
Subcomandante Marcos, the pipe-smoking political strategist, is the main attraction, his poetic speeches reducing observers to tears, his incendiary comments infuriating political opponents.
The Governor of Queretaro state, Mr Ignatio Loyola, warned Marcos to stay out of his town or face a firing squad. The rebel convoy pulled into Queretaro this week, where Marcos addressed a huge rally, called Mr Loyola an "imbecile", then asked permission from the crowd to stay the night. The governor left town for the day.
Members of President Vicente Fox's National Action Party (PAN) have criticised the march, with one legislator challenging Marcos to a duel.
"I will risk my presidency for this march," Mr Fox said.
The populist, centre-right President was elected last July on a platform offering recognition of rebel demands, winning a historic victory over the Institutional Revolutionary Party, (PRI), which ruled Mexico for 71 years.
Mr Fox has resisted calls to ban the march from Mexico's powerful business lobby, who claimed the event would inhibit foreign investment.
The left-leaning Party of the Democratic Revolution (PRD), which suffered a dismal defeat in last year's elections, is uneasy
about the rebel march, which threatens to become the clarion call for the launch of a New Mexican Left, stealing disillusioned supporters away from the parliamentary left.
"We're not in the least interested in the Zapatistas," the party's general secretary, Mr Jesus Zambrano, said, in a recent interview. But PRD supporters have flocked to the Zapatista march, which has injected fresh energy into the battered left.
Mr Fox has pressed the rebel leadership to sign a peace deal when they reach Mexico City, but his pleas have fallen on deaf ears, as the rebels demand the fulfilment of three goodwill "signals", including the dismantling of three army camps in Chiapas and the release of 60 Zapatista prisoners.
Mr Fox initially agreed to comply with the rebel requests, but has since backed down, blocking a return to dialogue.
The ousted PRI party sent 50,000 troops into Chiapas in 1995, besieging rebel communities. They also poured billions of dollars into the state, hoping to wean peasant farmers away from the rebel movement. The strategy failed as the Zapatista movement went underground, organising its own autonomous structures.
The Zapatista march reaches its climax on Sunday in Mexico's giant central square.