MEXICO CITY Charismatic leftist Andres Manuel Lopez Obrador came within a whisker of winning Mexico's presidency in 2006 but is struggling to build momentum for his campaign this year.
Often referred to as AMLO or "Peje" - a type of tough swamp fish in his native state of Tabasco - Lopez Obrador, 58, has long been famous for leading his supporters out on huge protest marches and making impassioned speeches condemning Mexico's "mafia" of rich and powerful oligarchs.
He brought stretches of the capital to a standstill in 2006 after crying foul over his loss to President Felipe Calderon, though his protests eventually alienated many supporters.
This time around he has toned down his rhetoric, and has reached out to the business community and pledged to curb monopolies. He has also called for a "loving republic," leading some pundits to now dub him as AMLOVE.
The silver-haired politician was born in the small town of Macuspana in Tabasco, where he began his career working with the government to help indigenous people.
He first joined the then-ruling Institutional Revolutionary Party (PRI), but abandoned it to help found the leftist Party of the Democratic Revolution (PRD) in 1988.
In 1994, Lopez Obrador ran for governor of Tabasco but lost to the PRI in a controversial election that he challenged with protest marches.
He then shot to national prominence in 2000 when he won the mayoral race in Mexico City just as Vicente Fox, like Calderon a member of the conservative National Action Party (PAN), became president and ended seven decades of rule of the PRI.
As mayor of the capital until 2005, Lopez Obrador built a loyal base by establishing a popular pension scheme and other social welfare programs. He also oversaw large-scale construction projects.
In 2006, Lopez Obrador waged a divisive campaign against Calderon under the slogan, "The poor first." Calderon hit back with a negative campaign in which he portrayed the leftist as an irresponsible populist who would bankrupt Mexico.
In Calderon's commercials, images of Lopez Obrador were flashed alongside those of leftist Venezuelan President Hugo Chavez beneath the slogan, "A danger to Mexico."
Lopez Obrador lost by less than 1 percentage point and led protests calling for a recount, declaring himself the rightful president of Mexico. Blockades mounted as part of the protests held up traffic in central boulevards of the capital for weeks.
Afterwards, Lopez Obrador toured every one of Mexico's 2,438 municipalities building up a network of grass-roots supporters that he called the Movement for National Regeneration.
He launched his 2012 campaign promising to rescue Mexico from rampant drug violence by providing jobs and services in the poor neighborhoods where most drug cartel hit men come from. Kicking off his campaign, he argued that the other candidates all represent the old system while he stands for real reform.
"There are four candidates but, with all respect, there are only two projects," he said. "They essentially represent more of the same and we represent the possibility of true change."
His new rhetoric, however, has so far failed to reignite voters' enthusiasm and most opinion polls show him stuck in third place. One survey published on April 19 did, however, show him overtaking PAN candidate Josefina Vazquez Mota.
Lopez Obrador in January conceded that his 2006 protests that gridlocked the capital cost him much support.
"There are people ... who still question me about it," he told Reuters. "Even though they weren't there."
(Reporting By Ioan Grillo; Editing by Will Dunham)