Mexico City: Mexican leftist presidential candidate Andres Manuel Lopez Obrador has said he will mount court challenges against the results of the July 1 elections, claiming vote buying and campaign overspending by the winner of official vote counts, Enrique Pena Nieto.

The Monday's announcement comes amid rising calls to investigate what appears to have been the distribution of thousands of prepaid gift cards to voters prior to the elections, and allegations by Lopez Obrador's supporters that some state government officials passed funds to Pena Nieto's campaign effort.

Lopez Obrador finished about 6.6 percentage points behind Pena Nieto of the old ruling Institutional Revolutionary Party, or PRI.

Even President Felipe Calderon, who suffered his own post-electoral dispute with Lopez Obrador following the 2006 elections, called for an investigation into the vote buying allegations and electoral reforms to prevent such practices in the future.

"The issue of the (gift) cards, the accounts and all, is an issue that I don't know if it will be sufficient to overturn an election with these margins, but it should be resolved," Calderon said.

"We cannot just accept this and say 'a little bit doesn't hurt'," Calderon told a local radio station. Referring to excessive campaign spending, Calderon said "every day more evidence is coming out, it's worrisome."

"I think electoral authorities should have a change of heart and punish this," Calderon said. Referring to possible measures against campaign overspending for future elections, he said "I think this is the big reform that Mexico still lacks."

And Calderon suggested for the first time the issue could play a role in Pena Nieto's transition period; he is scheduled to take office Dec. 1. He won office largely on promises the PRI had left behind the vote-buying and repressive tactics it used to hold on to Mexico's presidency from 1929 to 2000.

"I think this could be a smooth transition, if this is resolved correctly," Calderon said of the allegations. However, it is unclear whether Calderon's conservative National Action Party will join Lopez Obrador in the court challenges.


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