Activists opposed to the victory of Enrique Pena Nieto in Mexico's presidential election have called for a national "megamarch" Saturday to protest the results.
Pena Nieto, from the Institutional Revolutionary Party (PRI), decisively won Mexico's presidential election Sunday, a result the country's independent election authority confirmed on Friday.
Leftist Andres Manuel Lopez Obrador, who came in second, claimed Pena Nieto is guilty of vote-buying, enjoyed media coverage biased in his favor and broke campaign spending limits.
Lopez Obrador, from the leftist Party of the Democratic Revolution (PRD), held protests that virtually paralyzed Mexico City for more than a month when he lost the last presidential election in 2006 by less than one percent and claimed fraud.
However Lopez Obrador, who lost this time by more than six points, said he is not behind the Saturday march. The event is being organized online and via flyers handed out in the street.
"We do not want Pena Nieto or his oppressive government - Revolution!" screams a Facebook page dedicated to the march.
The PRI was synonymous with the Mexican state as it governed for 71 years until 2000 using a mixture of patronage, repression, rigged elections and bribery.
Octavio Aguilar, a senior campaign official for candidate Josefina Vazquez Mota of the ruling National Action Party (PAN), estimated that the PRI spent up to $500 million getting Pena Nieto elected, shattering the legal campaign spending limit of $30 million.
"That's is the problem with this democracy -- the one who has the most money buys the election," Aguilar told AFP.
The fraud was not at the ballot box, but in the river of cash the PRI used to pay for everything from gift cards to campaign paraphernalia to years of favorable TV coverage, he said.
The Facebook page claims it was put up by a "group of Mexican citizens tired of electoral fraud and the theft and unmeasured abuse of our national resources." Similar comments are found on Twitter under different hash tags.
The site includes plenty of pro-Lopez Obrador and anti-PRI pictures.
Students of the #YoSoy123 protest movement, which have organized several Mexico City marches in the past weeks, said they are not behind the Saturday protest.
The Mexico City metro area has a population of 21 million and is a bastion of the country's political left, so gathering a large crowd for an anti-PRI march is hardly a challenge.
A seemingly impromptu march on July 2, one day after the election, protesting Pena Nieto's tainted victory gathered more than 25,000 people, according to city police.
The PRI was synonymous with the Mexican state as it governed for seven decades until 2000, often using a mixture of patronage, repression, rigged elections and bribery.