The charismatic and combative leftist who paralyzed the streets of Mexico City after narrowly losing the country's last presidential election will make another run next year after winning an opinion poll released by his party on Tuesday.
A hugely popular candidate in 2006, Andres Manuel Lopez Obrador now is seen as a long shot to stop Mexico's Institutional Revolutionary Party, or PRI, from regaining the presidency in 2012.
Enrique Pena Nieto, the telegenic leading candidate for the PRI, is far ahead of his potential rivals, topping Lopez Obrador by 23 points in an October poll. But Lopez Obrador has a core of passionate supporters who say he was cheated of victory in 2006 and who often refer to him as Mexico's legitimate president.
The Democratic Revolution Party, or PRD, is the first of Mexico's three major parties to select a candidate for the campaign, which legally can't begin until February. Lopez Obrador's main rival for the nomination, Mexico City Mayor Marcelo Ebrard, said he would support the results of the poll, which asked 6,000 voters of all parties which man they preferred.
Lopez Obrador, 58, said his first task would be to unify the country's array of left-leaning parties, something that should be easy since two of the main small parties have been openly promoting his candidacy with radio and television advertisements for more than a year.
"We'll go forward together, without hatred or rancor, to construct a country with more love, with a social conscience and spiritual greatness," he said.
Lopez Obrador began his political career with the PRI in the Gulf coast state of Tabasco, but he left the party to support the 1988 presidential campaign of Cuauhtemoc Cardenas, a movement that gave birth to the PRD.
In 1994, he lost a Tabasco state governor's election that many watchdog groups said the PRI won by fraud. He later served as president of the Democratic Revolution Party.
Lopez Obrador tempered his firebrand reputation after winning election as Mexico City mayor in 2000, working with business groups and building large public works projects. He frequently squabbled with then-President Vicente Fox, whose government unsuccessfully tried to have him removed from office in a dispute over a hospital access road.
After Lopez Obrador narrowly lost the last election to President Felipe Calderon of the conservative National Action Party, or PAN, his supporters occupied the Zocalo, the main plaza in Mexico City, and blocked the city's elegant Reforma Avenue for weeks, claiming the election was stolen.
That reaction began to dent Lopez Obrador's popularity, and many Mexicans were enraged at his movement for blocking traffic and straining daily life.
Lopez Obrador cooled his rhetoric this year, taking a more conciliatory tone toward the wealthy and business interests. Still, Ebrard argued that he appealed to a broader segment of voters outside the party.
"It seems to me that Marcelo had more opportunity to grow in popularity," said political analyst Jose Antonio Crespo. "Lopez Obrador, despite his more moderate discourse, won't attract independent voters, or the protest vote against the PAN ... Marcelo had a greater possibility of moving into first or second place."
The PRI held power for seven decades until losing in 2000, and polls show it making a comeback across the nation, partly due to weariness with 11 years of National Action governments and horror at the estimated 40,000 drug war deaths since Calderon ramped up the fight against cartels.
Pena Nieto, a 45-year-old former governor of the state of Mexico, has led in all recent national polls. The majority of Mexican voters are centrists and the polls show their biggest concerns are security and the economy.
Democratic Revolution, meanwhile, has been split by feuding and it has lost much of its support even in its strongholds.
Preliminary results show the PRI winning Sunday's gubernatorial election in Michoacan, Calderon's home state and the place where he launched the war against the cartels. The PRD has governed there for 10 years, but it finished third behind National Action.
Recent polls show that the PRI even has a chance to win back the mayorship of Mexico City, where the PRD has governed since 1997.
In his concession speech, Ebrard emphasized the need to unite the PRD.
"A divided left would only go to the precipice," he said. "I will never be the person who leads Mexico's chances for change to failure."
Olga Rodriguez and Michael Weissenstein contributed.