Mexico's leftist presidential candidate says he is mounting a court challenge against the results of the July 1 elections, claiming vote-buying and campaign overspending by winner Enrique Pena Nieto.
Andres Manuel Lopez Obrador says his team is gathering evidence that state officials gave money to Pena Nieto's Institutional Revolutionary Party.
Lopez Obrador said Monday he plans to file the challenges by Thursday.
It remains unclear whether President Felipe Calderon's National Action Party will join the court challenges. National Action Party leader Gustavo A. Madero said there was evidence that state governors from Pena Nieto's party may have used public funds to support his campaign. Pena Nieto won the race by a margin of about 6.6 percentage points.
Madero said his party is talking to Lopez Obrador's group about the complaints.