Mexico's electoral authorities say only one of three independent candidates for president who initially seemed to have gathered the necessary number of signatures to make the ballot appears to have actually qualified after a detailed review.

Margarita Zavala narrowly surpassed the 866,593 required qualifying signatures for the July 1 election. She is a two-time elected lawmaker and wife of former President Felipe Calderon.

The National Electoral Institute said Friday at a news conference that former Nuevo Leon state Gov. Jaime Rodriguez and little known candidate Armando Rios Piter presented petitions with too many irregularities to qualify.

The two candidates will have five days to make arguments about disqualified signatures. The electoral authorities will make a final determination of who makes the ballot March 29.