Enrique Peña Nieto, the candidate of the Institutional Revolutionary Party, or PRI, won Mexico's July 1 presidential election with 38.21 percent of the vote, electoral authorities said Friday.

Leftist Andres Manuel Lopez Obrador finished second, with 31.59 percent, followed by the standard-bearer of the governing conservative National Action Party, Josefina Vazquez Mota, who garnered 25.41 percent of the vote.

Gabriel Quadri, representing the tiny Panal party, picked up 2.29 percent.

Release of the official results was delayed to permit a manual tally of the ballots from more than half of the polling places, as ordered by the Federal Electoral Institute, or IFE.

National Action, in power since December 2000, said earlier this week that despite problems with the process, it will respect the outcome of the elections.

Lopez Obrador, however, said he plans to formally challenge the outcome, based on credible allegations of vote-buying by the PRI, which became notorious for electoral chicanery during its 1929-2000 hammerlock on the presidency.

"There was a lack of equity before, during and after the electoral process, above all in regard to the covert political propaganda on radio and television in favor of candidate Enrique Peña Nieto," the left's delegate to the IFE, Camerino Marquez, said Friday, alluding to press reports that Mexico's dominant TV network, Televisa, systematically promoted the PRI hopeful.

The election results may also face legal challenges from a nonpartisan student movement that has documented instances of vote-buying, tampering with ballots and other irregularities.

The IFE stressed that the official tally closely tracked the preliminary results released hours after the polls closed last Sunday.

The manual verification of vote totals was "the broadest and most transparent in Mexico's electoral history," the IFE said, pointing to the presence of thousands of observers during the process. EFE