Shortly before midnight on September 15, the president, Vicente Fox, is due in Mexico City's main square, the Zocalo, to kick off the country's Independence Day celebrations for the last time before he leaves office. Whether that will actually happen is anybody's guess.
For his part, the defeated left-wing presidential candidate, Andres Manuel Lopez Obrador, has different plans for the square on that day.
Since July 30 his supporters have been in "permanent assembly" in the Zocalo with dozens of protest camps stretching 9km in the heart of one of the world's biggest cities.
They have staged rallies in which hundreds of thousands have participated, with some estimating that one in particular attracted more than a million protesters.
They refuse to accept the official results of the July 2 presidential elections, validated by the country's top electoral court on September 5. The court officially declared the conservative Felipe Calderon as president-elect, rejecting Lopez Obrador's demands for a full recount.
Lopez Obrador's programme for Independence Day includes holding a National Democratic Convention to discuss forming a parallel government that he and his supporters call "the legitimate government" that would rule from the streets without recourse to the official government.
If the rival schedules were not enough of a headache there is the further complication that on September 16 the armed forces parade through the streets of downtown Mexico to commemorate independence from Spain.
The route of the parade is currently under the control of Lopez Obrador's followers. Will they clear the way for the army? Or will they have to be removed by force?
Everyone hopes the protests
will not turn violent
It is a tough call for Lopez Obrador, the government and the army as no one wants the political tension to turn into violence, which would be a lose-lose situation for all concerned.
Lopez Obrador won the last confrontation on September 1 when members of his Democratic Revolution party seized the podium and prevented Fox from delivering his final State of the Nation address.
He calls the protests "civil resistance" and says he will take things as far as they have to go, maybe towards a "revolution". He will not give up and will not admit defeat to his rival Calderon, whom he accuses of cheating his way to the top job with the help of fellow party member Fox and his government.
Margin of error
The top electoral court, whose decision is irrevocable, did observe that the public backing of Calderon by Fox and his government represented the biggest risk for the validity of the elections, but declined to annul the vote.
This election will go down in history as Mexico's closest and most controversial ever with Calderon prevailing by a razor-thin margin of just over half a per cent.
The preliminary results released a day after voting had given Calderon an advantage of 402,708 votes over Lopez Obrador, but that dwindled to 243,934 a few days later and the difference now is only 233,831 according to the final official results.
Interestingly enough that final figure is less than the 237,736 votes annulled by the electoral court after finding irregularities in the results and deciding to recount only nine per cent of the total vote.
Calderon proudly holds his
That in itself leaves room for suspicion and makes many ask one truly valid question: why did the court not order a full recount that would have appeased the nation and possibly reconfirmed Calderon's victory anyway, or otherwise would have given his rival a victory he would have deserved?
Nobody seems to have a straightforward answer to that question. Lopez Obrador's followers, including some of the country's intellectuals and artists, say that both the court and the Federal Electoral Institute are infiltrated by the government or at least some of their members are under its influence.
No turning back
One can understand why some Mexicans would believe that given the country's long history of electoral fraud and manipulation during 70 years of rule by the Revolutionary Institutional Party which ended in 2000 when Fox's National Action Party broke that chain.
That was a great day in Mexico's path to democracy and the current dispute might just be another inevitable – and very painful - step along that path and a real test for a relatively young democracy in a country so sharply divided between rich and poor.
There are doubts over whether Lopez Obrador knows what he is doing.
He has transformed himself from a moderate left-leaning candidate to an ever-more radical and daring "resistance" leader and many wonder why he could not just wait till 2012 to win the next election which would not have been too hard given his popularity as a former mayor of Mexico City and his obvious capacity to mobilise the masses.
Perhaps Lopez Obrador realises that if he gives up now, his supporters will simply look for another leader, now that all scenarios seem possible, including that of an armed rebellion.
It is the first time in Mexico that an institutionalised political alliance has fused with a massive protest movement comprised of people who have lost faith in the traditional political parties.
In a nation of 100 million inhabitants, more than 50 per cent of the population is poor and many blame consecutive governments for failing to halt the hunger and poverty in the lower classes.
Lopez Obrador is unlikely to
back down now
If the cold winter of Mexico City does not send the Zocalo campers home, then Lopez Obrador's followers might manage to keep Calderon from being sworn in before congress on December 1 and turn his most glorious day-to-be into his first failure as a president. They could, of course, also try to swear in their own president of Mexico.
But if Mexicans have managed for thousands of years to rule and build civilisations, they will certainly manage to solve the current conundrum of "One Mexico, Two Presidents", hopefully without plunging into violence and chaos.
The real challenge for everyone lies in solving the real issues behind the conundrum and giving Mexicans a more dignified and satisfactory life.