Thousands of Mexicans rallied to show support for "shadow president" Manuel Lopez Obrador -- who believes his country's top job was stolen from him in 2006 -- at the mid-point of his would-be presidential term.

A 56-year-old leftist former Mexico City mayor, Lopez Obrador's hopes of leading this country of about 106 million were dashed (but not for long) when official results showed he lost the 2006 race by just some 230,000 votes.

He charges that a careful recount of the vote was carefully avoided by those who had the authority to duly pursue one.

Poised to emerge as a potential alternative to the conservative PAN party of President Felipe Calderon in 2012, Lopez Obrador has pushed on, day after day, insisting that he is, in fact, Mexico's legitimate president.

He works out of an elegant office in an old mansion in Mexico City, in front of a portrait in which he is pictured wearing the presidential sash.

Tens of thousands of supporters packed Mexico City's landmark Zocalo square Sunday to hear Lopez Obrador underscore that power has been usurped from the Mexican people, by -- in his view -- a "mafia" of powerful colluding political and business interests.

"They themselves know that this movement is the only thing that can take them on, and that can stop them," he told a sea of supporters. Lopez Obrador claims 2.3 million supporters have signed up in support of his movement nationwide.

In the past three years, Lopez Obrador has criss-crossed the country on a busy endless campaign, and has written letters to world leaders including US President Barack Obama.

He even has a complete shadow cabinet, and has been active in keeping the protest movement alive -- so much so that the traditional leftist Party of the Democratic Revolution has distanced itself from him.