MEXICO LETTER:WHEREVER YOU go in Mexico, you'll run into Andrés Manuel López-Obrador.
The failed presidential candidate's well-groomed face, with its easy smile and crown of iron grey hair, stares from political murals and posters the length and breadth of the nation.
Until recently, these images seemed part of another age. Ever since he lost the election to conservative Felipe Calderón in 2006, López Obrador, or AMLO as he almost universally was known, has stood on the sidelines, protesting that he, in fact, is the legitimate president of Mexico. But after two years of Calderón in Los Pinos, the presidential palace, few people were listening. AMLO seemed frozen in time.
However, walking through the Zócalo, Mexico City's mammoth main square with its enormous Mexican tricolour, AMLO was once again everywhere. His face was on T-shirts, car stickers, key rings. They even recycled his old campaign slogan - "Smile - we're going to win."
AMLO was the man holding the microphone, but the thousands who packed the Zócalo on Sunday were there because of one black, viscous and expensive substance: oil.
President Calderón, worried by the drop in production from state oil monopoly Pemex, last week proposed a reform that would allow foreign companies to drill for, transport and refine oil.
For the people in the Zócalo, and millions of others across the country, this was nothing short of treason.
"That moron [ Calderón] wants to sell our riches to foreign oil firms, and take this country back to colonial times!" said José Paredes, a 68-year-old from outside Mexico City, who attended the rally with a cardboard model of an oil rig tied to his head.
Oil is a touchy subject in Mexico. In 1938, President Lázaro Cárdenas seized the holdings of foreign, mostly American, oil firms, after they refused a government order to improve worker conditions. Cárdenas enshrined the government's "subsoil rights" in the constitution, and since then state oil firm Petroleos Mexicanos - Pemex - has been a symbol of pride and sovereignty.
For those with their hands on the levers of power, it has also been something resembling a cash point. Oil money makes up nearly half of the federal government's budget, and Pemex workers are among the most privileged in the country - they even have their own hospitals.
With so many snouts in the trough, Pemex has frequently found itself short of cash. It knows there is oil in the deep waters of the Gulf of Mexico, but years of neglect have left it with no idea how to get it out of the ground. The foreign oil firms - Exxon, Shell, and others - do know. But they're not sharing any secrets till they're guaranteed a slice of the profits from these rich oil fields. And that means picking a fight with Lázaro Cárdenas, and AMLO.
Speaking in the dull heat of Mexico's spring, with a vigilant police helicopter circling above, AMLO was a rallying point for protesters of all shapes and sizes. At his behest, thousands of women have formed militant neighbourhood brigades to protest at the energy reforms. Columns of women dressed in white marched into the Zócalo chanting, "It is an honour to stand with López Obrador!" Others simply drifted in wearing their T-shirts from the election, ready to denounce Calderón and all his works.
When he finally came to the microphone, however, AMLO was something of an anticlimax. The crowd had been whipped into a frenzy by a series of warm-up speakers, but AMLO himself struggled to maintain interest. In a long, staccato speech, he listed the ways in which the government had betrayed the people, manipulated the press and worked hand in hand with foreign businessmen.
The crowd seemed restless, letting out muted cheers when he struck emotive points, and interrupting with passionate chants of "The people united will never be defeated!" But long before the end of the speech, individuals were drifting towards the metro stations, perhaps tired after three hours of protesting in the heat, or eager to get home for the afternoon's football.
Even if the movement is bigger than the man, AMLO's face is back on people's minds and chests. And after two long years of talking only about himself, he now has a fiery topic to take to the people. Some 100,000 people turned out to protest when he lost the election, paralysing Mexico City for weeks on end. Who knows how many he will conjure up to obstruct what would be a historic change to the nation's prize asset?
"The movement is every one of us, but López Obrador is the leader," Guillermo San Juan, a 47-year-old-factory worker told me. "Foreigners have taken Mexico's gold, Mexico's silver. We cannot let them take the oil."