A full three days after the election, Mexico still has no new President. With the two front-runners claiming victory, and separated by less than 1 per cent of the vote, the country's election watchdog has declared the result too close to call. An official count begins today; it could be a week before there is a result - and then only if there is no subsequent challenge from either of the main parties.

The advantage lies with the Conservative candidate, Felipe Calderon; the initial count gave him 400,000 votes more than his left-wing rival, Andres Manuel Lopez Obrador. A victory for Mr Calderon would mean that Mexico had bucked the leftward trend in Latin America and chosen to continue the course set by the outgoing President, Vicente Fox. The US administration would be happy, and so - initially - would investors. There had been fears that Mr Obrador, former mayor of Mexico City, champion of the poor, might call his supporters on to the streets. So far, to his credit, he has refrained from appealing to people-power to override the electoral process. He has pledged instead to use every legal avenue to challenge the result. That could include another recount and a battle through the courts.

Whatever happens, the delay allows plenty of time for mischief-making. Genuine democracy in Mexico is only six years old and Mr Obrador's supporters already believe they were robbed. Their leader will have to show a cool head and the counting will have to be both punctilious and transparent if potentially explosive discontent is to be avoided.

Anticipating victory, Mr Calderon has already undertaken to form a conciliatory government. This may, however, be more easily said than done. The voters had a clear choice between left and right, between state intervention and the free market. They were evenly split, with the balance held by the country's once dominant, but politically amorphous, Institutional Revolutionary Party, which could join the winner in a coalition.

Mexico may not quite have followed the trend to the left in Latin America, but its election fits another pattern. It is the latest democratic vote to have ended, in effect, in a draw, producing the very uncertainty that elections were supposed to prevent.

Since the epic stand-off between George Bush and Al Gore for the US Presidency in 2000, we have seen deadlocked elections in Germany, Ukraine, Italy and, most recently, the Czech Republic. On current figures, it is even predicted that the next British general election could be drawn. Whatever factors produce such results, a tied election inevitably tests other aspects of the state - including the courts and public civility - to their limits. We hope that in Mexico they will be strong enough to stand the strain.