The world’s recent run of close elections has generated some petulant reactions – recall Silvio Berlusconi’s refusal to concede defeat in Italy – but perhaps none so extreme as in Mexico.

The presidential election, held in July, delivered victory to the centre-right’s Felipe Calderon by the very narrow margin of 44,000 votes out of more than 40 million (see figures here).

A partial recount was ordered, which failed to turn up significant irregularities, and the supreme court duly certified the result.

Calderon will be sworn in next week. But his rival, left-winger Manuel Lopez Obrador, continues to maintain that the election was rigged, and now has stolen a march by holding his own “inauguration”.

As the BBC reports, Lopez Obrador was “sworn in” on Monday in front of a crowd of 100,000 of his supporters in Mexico City’s main square. He pledged “to serve loyally and patriotically as legitimate president of Mexico”, and “promised he will do everything he can to hamper the government of Mr Calderon”.

It looks as if Lopez Obrador, having passed the point where it was possible to concede gracefully, is digging himself into a deeper hole.

Although the “inauguration” is fundamentally symbolic – as AP reports, “His parallel government, with a 12-member cabinet, will not collect taxes or try to make laws” – it threatens a possible escalation of chaos in a country that could do with some stability.

It also indicates a worrying tendency of some elements of the Latin American left to not recognise the legitimacy of a democratic verdict. In the past, when stolen elections were a way of life, they had very good reasons for that attitude, but Lopez Obrador seems unable to recognise that times have changed.

According to the BBC, “many Mexicans are tired of conflict and long for a return to normality”, and even “some of his supporters think his alternative inauguration is ill-advised and politically irresponsible.”

The next big test of democracy in the region will be Venezuela’s election on 3 December, when authoritarian leftist president Hugo Chavez is seeking a further six-year term.

Opinion polls put him well ahead, but the possibility of yet another close election should not be discounted.