MEXICO CITY (AP) _ Mexican lawmakers handed federal investigators a box of evidence on Tuesday that they claim shows that two of President Vicente Fox's stepsons were involved in fraud and illicit enrichment through real estate deals.

The action by a special congressional committee came less then two months before the July 2 presidential elections, in which Felipe Calderon of Fox's Conservative National Action Party is fighting a tight race against leftist Andres Manuel Lopez Obrador.

Many of the committee's most vocal accusers are from Lopez Obrador's leftist Democratic Revolution Party, and some National Action lawmakers call the accusations an attempt to damage Calderon's campaign.

The committee's investigation focuses on the construction and real estate dealings of Manuel Bribiesca and his brother Jorge Alberto, sons of first lady Marta Sahagun from her first marriage. Fox and Sahagun, who wed in 2001, have no children together.

The committee, which was set up last June, claims the Bribiesca brothers conspired with officials to buy government properties at a fraction of their worth. Among the evidence are copies of checks allegedly used to buy the properties and documents recording the purchases.

The Bribiesca brothers deny the accusations. Fox and Sahagun have come out in support of the men.

The committee presented the evidence to the attorney general's office, which will decide if there is sufficient cause to bring criminal charges against the brothers.