By Lizbeth Diaz
MEXICO CITY (Reuters) - Mexico's leftist runner-up in the July 1 presidential election stepped up his campaign on Wednesday to annul the vote by accusing President-elect Enrique Pena Nieto of using laundered money to fund his campaign.
Andres Manuel Lopez Obrador said he had found evidence that shell companies were set up to funnel money into the coffers of Pena Nieto's Institutional Revolutionary Party, or PRI, during the campaign.
Over 100 million pesos ($7.6 million) were used to buy prepaid debit cards handed out to voters to support Pena Nieto, Lopez Obrador alleged.
"We have sufficient proof to say that Pena Nieto's campaign used illicit funds," he told a news conference after bringing boxes of evidence to authorities at the electoral tribunal. "This is money laundering."
Lopez Obrador has accused Pena Nieto of buying votes and overspending for the campaign, demanding a recount soon after the election. But this was the first time he made specific money-laundering allegations.
The PRI dismissed the claims.
"We reject as inadmissible the accusations of money laundering, which constitute a flagrant defamation," the party said in a statement.
"(Lopez Obrador) demanded a recount and when it confirmed the result, he changed his argument to massive vote buying, which did not stand and now he is launching another unlikely charge of money laundering," the PRI said.
Lopez Obrador named several companies he said had been used to channel money to the debit cards, saying some had false addresses, as he presented a 32-page document to the media outlining the allegations.
The electoral tribunal has until September to consider complaints and declare an official winner.
Pena Nieto, a former governor of Mexico's most populous state, beat Lopez Obrador in the election by more than 6 percentage points. This week, he met outgoing President Felipe Calderon to discuss the transition to his new government.
Pena Nieto has called his win "categorical," but said he would wait until the electoral tribunal made its ruling to name an official transition team.
"I am hoping that the parties will take a democratic stance and respect the results of this election," Pena Nieto said earlier on Wednesday. "I will be respectful (of opposition voices) as long as they stay peaceful and legal."
Lopez Obrador lost the 2006 race to Calderon by less than 1 percentage point. Following that defeat, he also contested the results, mounting protests that choked Mexico City for weeks.
Political analysts said Lopez Obrador's series of allegations lacked strong evidence and they speculated that his main objective was to hold on to his leadership position in the political left rather than win his battle in court to void the election.
"It is a show," said political analyst Fernando Dworak. "Even though his evidence is weak, it foments a story of conspiracy and fraud. This keeps his base mobilized."
Calderon's conservative National Action Party, or PAN, succeeded in ousting the PRI from the presidency in a 2000 election after the party had ruled Mexico for seven decades straight. During that time, the PRI acquired a reputation for corruption, vote rigging and repressing protesters.
Accusing the centrist party of resorting to its old ways, Lopez Obrador, a former member of the PRI and ex-mayor of Mexico City, said he had not yet decided on a strategy if his complaints were rejected by the electoral authorities.
"It will be very serious if they don't act. We are going to use every legal recourse to investigate this and if there is impunity, we will target the responsible authorities," he said.
The dispute could become a stumbling block to Pena Nieto's effort to fast-track plans to reform labor, tax and energy laws that he says will speed up Mexico's lagging economic growth.
The PRI failed to win a majority in Congress and will need opposition support to push through its reforms.
The leftist Party of the Democratic Revolution, or PRD, which backed Lopez Obrador along with a coalition of leftist parties, is the No. 2 force in the lower house.
($1 = 13.1074 Mexican pesos)
(Writing by Mica Rosenberg; Editing by Peter Cooney)