The frustration and anger were palpable. Having come within a whisker of victory, the supporters of the left-wing candidate in Mexico’s presidential election refused to believe that Andreas Manuel López Obrador had been defeated by a mere 244,000 votes, out of 41 million cast on July 2. The result, giving victory to Felipe Calderón of the ruling National Action Party, had to be fraudulent. And at a weekend rally Señor López Obrador fed their anger, demanding a recount, promising to challenge the result in court and calling on his supporters to keep up their demonstrations.

His claim of vote fraud, including the computer manipulation of the results, has struck a chord with many Mexicans, used to the tricks used by the Institutional Revolutionary Party (PRI) to keep itself in power for 71 years. These included vote-rigging, unfair rulings by the Federal Electoral Tribunal and the use of a “computer crash” by the authorities in 1988 to eliminate the challenger’s lead.

Señor López Obrador, a former Mayor of Mexico City, cut his political teeth in those days in protests, shutting oil wells and blocking state government in his native Tabasco state. This time he accused the outgoing President Vincente Fox of illegally backing Señor Calderón with government funds, a charge he strongly denied. He said the Electoral Tribunal had become a pawn of the Right. And he and his supporters demanded a complete recount, “vote by vote” .

Such behaviour is as irresponsible as it is unjustified. None of the European election observers found any irregularity. There is no evidence of vote-tampering. And although it must be galling to lose by a mere 0.6 per cent of the vote, the Left has no grounds for a court challenge or the allegation of irregularities in 50,000 of the 130,000 polling stations.

Señor López Obrador’s premature claim of victory and his accusation that his opponent was backed by powerful figures in the richer north of Mexico have split the country along geographic, class and even racial lines. It is from the poorer south, where indigenous peoples have been struggling against rich landlords and exploitation, that Señor López Obrador draws his strength, as well as in the slums of Mexico City. His refusal to concede defeat will not only make it hard for Señor Calderón to tackle the country’s problems with any measure of consensus; it will also exacerbate underlying tensions within Mexico and threaten new fractures in a country that has seen more than its share of revolutions and social uprisings.

Any incitement to his followers to continue their demonstrations — even if they are ordered not to block the roads — could lead to violent clashes and rally support for a crackdown on all protest, a reimposition of quasi-military controls, a reversal of recent moves to embed democracy and human rights in Mexican society and increasing alarm north of the border. Those who would suffer most are Señor López Obrador’s supporters. He must pull back from such reckless incitement before it is too late.