Runner-up in Mexico's presidential election filing legal challenge
July 13, 2012 -- Updated 1136 GMT (1936 HKT)
Andres Manuel Lopez Obrador has said a partial recount was not enough to erase his doubts about the vote.
- Andres Manuel Lopez Obrador is refusing to concede in the presidential election
- He says he is filing a legal challenge because of allegations of vote-rigging
- Election officials: Enrique Pena Nieto won 38.21% of the votes, to Lopez Obrador's 31.59%
- The results remain unofficial until the country's electoral tribunal ratifies them
(CNN) -- The runner-up in Mexico's presidential election announced Thursday that he was filing a legal challenge to invalidate the vote.
Andres Manuel Lopez Obrador of the Democratic Revolution Party has said that presumptive President-elect Enrique Pena Nieto and his party bought millions of votes in the election, an accusation that party officials have denied.
Lopez Obrador has said a partial recount was not enough to erase his doubts about the vote.
"To proceed in another way would be to give up our fundamental rights," Lopez Obrador told reporters at a news conference.
A tally of returns released by Mexico's Federal Election Institute last week confirmed that Pena Nieto of the Institutional Revolutionary Party, or PRI, received 38.21% of the votes. Lopez Obrador garnered 31.59% of the votes, election officials said.
What can save Mexico?
Peña Nieto on the economy
Peña Nieto: Mexico's new face
The tally has been completed, but the results remain unofficial until the country's electoral tribunal ratifies them.
The tribunal will have until September 6 to complete its investigation and ratify -- or reverse -- the election results. The new president will be sworn in on December 1.
Lopez Obrador has criticized the election and refused to concede repeatedly over the past week, echoing comments he made in 2006 when election authorities said the leftist candidate narrowly lost the presidential vote to Felipe Calderon.
After that election, the former Mexico City mayor claimed election fraud and never conceded.
Back then, Lopez Obrador called himself "the legitimate president of Mexico," and his supporters protested nationwide. In Mexico City, they staged sit-ins and blockades.
Officials have called this year's election the most transparent in Mexico's history. It was the first election in which scanned copies of district-by-district election returns were posted on the Internet.
But accusations have arisen of electoral manipulation by the PRI.
Opponents of the PRI said they have video and photo evidence of the party buying votes through thousands of cards that could be redeemed for products at a chain of supermarkets.
The PRI has called the claims a farce and accused political opponents of staging the videos and photographs purported to show vote-buying.
CNN's Samira Said and Nick Parker contributed to this report.
Part of complete coverage on
Presumptive president-elect Enrique Peña Nieto talks to Fareed Zakaria about the drug war, immigration and the economy.
July 3, 2012 -- Updated 0934 GMT (1734 HKT)
The party that ruled Mexico for more than 70 years appears poised to return to power after election authorities projected Enrique Peña Nieto as the winner of the nation's presidential vote.
July 3, 2012 -- Updated 0019 GMT (0819 HKT)
Enrique Peña Nieto, the man election authorities project will be Mexico's next president, was governor, husband to TV star and a party's next hope.
July 2, 2012 -- Updated 1840 GMT (0240 HKT)
Mexico's election results raise issues rooted in the country's complicated political past that will play a critical role in shaping the nation's future.
July 3, 2012 -- Updated 0515 GMT (1315 HKT)
CNN's Rafael Romo reports on PRI's Enrique Peña Nieto and the return of the old guard.
July 3, 2012 -- Updated 0241 GMT (1041 HKT)
See the scenes from Mexico's election day and aftermath
A return of the PRI had worried many observers and politicians in the United States. So what's next?
How does the U.S. electoral system compare to Mexico's? One expert weighs in on eight things the U.S. system could learn from its southern neighbor.
See and hear from everyday Mexicans on what they thing the election means for them -- and for across the border.
June 26, 2012 -- Updated 1742 GMT (0142 HKT)
They love two countries, live in two worlds -- and fought to have their voices heard.
June 28, 2012 -- Updated 1054 GMT (1854 HKT)
They sport purple hair and piercings, plaid shirts and plastic aviator glasses. A guy with dreadlocks totes a bongo drum.
July 9, 2012 -- Updated 1633 GMT (0033 HKT)
CNN's Miguel Marquez reports that Mexico is a bright spot in an otherwise dreary world economy.
Don't let perceptions of Mexico fool you, writes Fareed Zakaria. It is quietly on the rise.
January 20, 2012 -- Updated 1403 GMT (2203 HKT)
There's the barrage of horror flick headlines every week, but the Mexican drug war, at its core, is about two numbers: 48,000 and 39 billion.
Follow the latest news, features and analysis from a Mexico perspective and in Spanish at CNNMexico.com
Today's five most popular stories