Mexico's highest electoral court says it has formally received the legal challenges filed by the second-place leftist candidate seeking to annul the July 1 presidential elections.

The challenges filed by leftist candidate Andres Manuel Lopez Obrador appear to face an uphill struggle given the 6.6.-percent margin of victory for the winner of the race, Enrique Pena Nieto.

Lopez Obrador claims Pena Nieto's campaign engaged in overspending and vote buying. The court says he submitted 38 boxes of evidence as part of the challenge.

Pena Nieto met with President Felipe Calderon at the presidential residence late Tuesday.

Calderon's office said the president promised to start "an orderly transition process" after the court rules on the challenges.