A charismatic politician who has been compared in the Mexican press to America's Bill Clinton and most recently, in his opponent's television ads, to Venezuela's Hugo Chavez, Andres Manuel Lopez Obrador has the support of millions of Mexico's poor, who believe he will keep his promise: "I will not steal, I will not lie, and I will not betray the people."

The 52-year-old widower representing the leftist Democratic Revolution Party is greeted enthusiastically in the tiniest villages and the largest slums, often by women wearing yellow T-shirts that read, "Andres Manuel, you are my rooster!"

However, his critics, whoich include many in the business world and Mexico's elite, see Obrador as an irresponsible populist who will ruin the country's fragile economy.

"He is a man of deep prejudices, and he doesn't think much of the Mexican bourgeoisie," Rossana Fuentes Berain, a political analyst at the Autonomous Technological Institute of Mexico, told the Los AngelesA Times.

As the mayor of Mexico City from 2000 to 2005, Obrador drove a cheap car, lived in a middle-class apartment, and won over the city's poor by creating a program that provided monthly $60 subsidies for all residents over 70. His efforts to improve the transportation system included building elevated roads and special bus lanes to relieve traffic congestion, the most important public works in the city in 20 years, according to the Los AngelesA Times.

He also hired former New York mayor Rudolph Giuliani to craft a zero-tolerance policy to help Mexico City's intractable crime problem.

However, under his leadership, several corruption scandals rocked the city and crime remained high. In an April 2006 Economist profile, Soledad Loaeza, a political scientist at the Colegio de México graduate school, said that if Obrador did not know of the corruption in the city government, "he should have."

Roberto Madrazo, one of Obrador's opponents in the presidential race, called the projects and handouts ploys that created debt without really fixing the city's problems.

In April 2005, the ruling Revolutionary Institutional Party, known by its Spanish initials, PRI, and ruling National Action Party legislators tried to impeach Obrador for refusing to listen to court rulings which demanded that he halt a road construction project. A successful conviction on criminal charges would have disqualified him from running for the presidency.

Congress voted to impeach him, but within days, more than 500,000 of his supporters took to the streets of Mexico City. A local judge tossed out the original complaint. The attorney general resigned, and President Vincente Fox announced that the case would not proceed.

Obrador returned to the mayor's office more popular than ever; polls showed his approval ratings above 80 percent%.

Obrador's hard-edged speeches during the impeachment proceedings furthered his reputation for stubborn defiance in the face of criticism which earned him the nickname "The Rock" as a child.

The eldest of eight children of a lower-middle-class family in the village of Tepetitan, in the state of Tabasco, Obrador dreamed of being a professional baseball player.

In the 1960s, his family moved to the nearby oil-rich boomtown of Villahermosa, where he soon became heavily involved with the PRI.

But by 1988, he became disillusioned with the party's treatment of the poor and helped form the new Democratic Revolution Party, or PRD.

Obrador has said he would like to raise the minimum wage -- now $4.50 a day -- and renegotiate parts of the North American Free Trade Agreement to better serve Mexico's small farmers. He said he also would turn back current efforts to privatize Mexico's energy resources and increase federal funding for the energy company Pemex, generally seen as an inefficient state monopoly.

In a Q & A with the Washington Post, Obrador rejected the suggestion that his administration would take an antagonistic stance toward the United States, as have the recently elected leftist leaders of Brazil, Venezuela and Bolivia.

"No. I cannot do that. We have 20 million Mexicans in the U.S. Eighty percent of our international trade is with the U.S. So [our policy] has to be different," he said.

-- Compiled by Leah Clapman for the Online NewsHour