Report from journalist Joaquin Lopez Doriga
Margarita Zavala was polling in the 2-5% range. Lopez Obrador has a clear lead but it's unclear where her votes will go in what's now a three-man race.
She is the wife of former President Felipe Calderon but quit the center-right National Action Party (PAN) in October to run as an independent.
Some polls put Lopez Obrador far ahead with a lead at 48% compared to 26% for his nearest rival.
The vote is July 1.
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