It is a hot afternoon in Oaxaca, a city surrounded by arid hills in southern Mexico, and Roberto Madrazo, one of the leading presidential candidates, is about to attend a lunch organized by the local Masonic fraternity.

A catchy, tropical jingle plays in the background: "He´ll have a firm hand, Mexico will change," goes one line. "Get rid of kidnappings, yes, Roberto can. Do away with violence, yes, Roberto can," goes another.

"How are you? Everything OK? I´m delighted," says a groomed Madrazo as he works almost every one of the more than 60 tables. He shakes hands with businessmen, kisses their wives as if they were old friends and poses for photographs with their blushing daughters.

Half an hour passes before he gets to his table.

This is Madrazo in his element - using his down-to-earth charm to win the votes for the July 2 presidential election.

In Oaxaca, at least, it seems all too easy. The poor and overwhelmingly rural state has remained a fortress of Madrazo´s Institutional Revolutionary Party (PRI), even when it lost the presidency in 2000 after 71 years of uninterrupted rule.

To judge by the 8,000 supporters at a local rally here, nothing is going to change.

"We are part of one big family and our surname is PRI," says Tomás Santiago López, a farmhand.

Madrazo´s problem is that not all of Mexico has Oaxaca´s blind - almost religious - faith in his party. The most recent poll has him battling for second place with Felipe Calderón of the center-right National Action Party (PAN). But both are still well shy of Andrés Manuel López Obrador, the hugely popular leftwing candidate.

What has proved a formidable source of strength in Oaxaca has often turned out to be a severe handicap in other states.

The PRI has become synonymous in the eyes of many voters with unbridled corruption, inefficiency and a disdain for democracy.

Of the three leading candidates, that is one reason Madrazo consistently takes the prize as the candidate with the highest rejection factor among voters.

Another is that the 53-year-old party veteran has earned a reputation as a Machiavellian politician.

In 2002, for example, he won the presidency of his party amid accusations of ballot-fixing - in some polling stations he even seemed to win more votes than there were voters.

His campaign has also suffered repeated setbacks since it began in January, including corruption scandals associated with the PRI, and bloody feuds and corrosive jealousies among party members.

Flying in a helicopter over Oaxacan mountains, Madrazo admits his campaign has had ups and downs. But he shrugs off suggestions that, with just 100 days to go, López Obrador´s lead is insurmountable.

"I am a marathon runner," he tells the FT (his best time is an impressive three hours and four minutes). "A marathon runner is never in first place at the start. You have to pace yourself."

Now that he and his party have chosen candidates for the congressional race, he says, the PRI´s notorious machinery will start to turn its wheels.

"The PRI has a structure, a grass-roots organization," he says. "No other party has a structure like ours."

Above all, though, Madrazo is confident he has the best proposals. He rejects the "neo-liberal model" of the last decade, and favors instead greater "social development along regional lines."

But he also advocates policies associated more closely with Calderón, his center-right competitor, such as opening up the country´s state-dominated energy sector to allow a bigger role for private companies.

"We have to go toward a progressive and rational center ground."

In Huautla, a town of about 15,000 perched precariously on a mountainside a six-hour drive from Oaxaca,

Madrazo gives a masterclass in how to get the crowd going. Thousands of poor, mainly indigenous Mexicans have been waiting impatiently, and now their man has arrived. They adorn him with a wreath of purple flowers, and dark-skinned men in white shirts and wide-brimmed hats blow horns made from cowhorns and conch shells.

Madrazo takes the microphone and, with translator at hand for those who only speak the local language, he opens up the throttle. The result is a speech thick with hope, enthusiasm and, above all, promises.

"We will give you doctors 24 hours a day," he says triumphantly. "We are going to turn into reality the Otitlán-Huautla-Xalapa highway," he vows.

"We are going to establish a development bank that helps farmers and gives them credit."

From the reaction in the crowd, the race in Oaxaca is already won.

As for winning in the rest of the country, Madrazo will have to run the best marathon of his life.