Mexican presidential candidate Andres Manuel Lopez Obrador lodged his first legal challenge to the result of the July 2 election, filing allegations of fraud in a case bound for the nation's electoral court this week. Leaders of Lopez Obrador's Party of the Democratic Revolution, in a complaint presented at the Federal Electoral Institute in Mexico City, cited mathematical errors in tallying the vote and ballot stuffing among its claims in a more than 900 page document, according to a summary of the filing made public last night.Lopez Obrador, at a rally of about 280,000 supporters in Mexico City July 8, said the election was marked by fraud and ballot tampering and vowed to demand a recount of all votes. Lopez Obrador lost the election to Felipe Calderon of the governing National Action Party by 243,934 votes of the 40.9 million valid ballots counted, a second tally last week showed. ``The only entity that can declare a president is the federal electoral court,'' said Horacio Duarte, a legislative deputy for Lopez Obrador's party after submitting the document. The Mexico City-based electoral institute, which last week said Calderon won a final count of votes, has three days to hand Lopez Obrador's complaint to the Federal Electoral Court. During that period, other parties will have access to the claim and may present evidence to dispute it.