MEXICO CITY — The runner-up in Mexico's presidential election, leftist candidate Andres Manuel Lopez Obrador, demanded Tuesday a full recount of the ballots, pointing to "inconsistencies."

"We have presented a formal request on behalf of the (leftist) coalition asking for a recount and counting the votes cast in the 143,000 ballot boxes installed for the presidential elections," campaign coordinator Ricardo Monreal said at a press conference alongside Lopez Obrador.

Monreal explained that an "investigation" by the leftist coalition led by the Democratic Revolution Party, or PRD, had so far found that 113,855 out of the 143,000 ballot boxes "that were installed had inconsistencies."

"There is no doubt that there was not a fair and transparent election," said Lopez Obrador, accusing the Institutional Revolutionary Party (PRI) of having bought "millions of votes.

Observers worry that Lopez Obrador's refusal to concede to rival Enrique Pena Nieto could trigger a repeat of the 2006 presidential election, when he lost by less than one percent, claimed fraud and organized mass protests that paralyzed Mexico City for more than a month.

The first official results from Sunday's vote showed Lopez Obrador with 31 percent of the vote against 38 percent for Pena Nieto of the PRI -- a much wider margin than six years ago.

Lopez Obrador claims that the PRI, through its national party and governors, spent millions of pesos buying votes. He also charged that the news media heavily favored the PRI and that the party shattered campaign spending limits.

The PRI was synonymous with the Mexican state as it governed for seven decades until 2000 using a mixture of pervasive patronage, selective repression, rigged elections and widespread bribery.