Margarita Zavala's unexpected announcement came one week after a midterm election in which the National Action Party suffered its worst showing at Mexico's polls since 1991.
The scandal-ridden Green Party said it had nothing to do with supportive messages sent by Mexico's national soccer coach and others, which is illegal under electoral rules. Rival parties cry foul.
Turns out "El Bronco" spent thirty years in Mexico's ruling party. But even so, his landslide victory in Nuevo Leon marks a turning point — away from Mexico's political status quo.
Indie candidates also stormed to victory in key races in Jalisco, while the upstart leftist Morena movement made gains in Mexico City and in Congress. One man is killed in Guerrero.
Protesters burned ballots and attacked polling places in Guerrero, Oaxaca, and Chiapas. Exit polls were suggesting tight races in key state governor races, including Nuevo Leon, where indie candidate "El Bronco" was pulling ahead.
Remember 2000? Fifteen years since the transition to a multi-party democracy, Mexico's PRI machine is back in power and presiding over a fearful, sour midterm vote. President Peña Nieto's party will likely retain control of Congress.
Yakiri Rubio, 21, made headlines for stabbing a sexual attacker 14 times. Now she wants to be a representative for the tough Mexico City barrio of Tepito. "I know the party is using me to get more votes," she tells us.
Acting in ways that are anything but green, Mexico's "ecological" political group blankets cities with its aggressive ads. The Green Party's success is linked to the goals of the ruling PRI and President Enrique Peña Nieto.
Mexico's largest dissident teachers union CNTE carried out attacks against electoral offices in five states. A strike in Oaxaca is affecting 1 million students, as federal officials bowed to a demand on education reform.
A Mexico City newspaper said as many as 70 political attacks have occurred since February, as Mexico prepares to elect 500 lawmakers, nine governors, and hundreds of local office-holders.
With the case of the 43 missing students still looming over the state, Guerrero officials now say another probably mass disappearance took place after unknown men entered a town to 'free' it from a drug gang.
Scores of families have fled their homes in Guerrero, becoming "internally displaced" in the violent conflict over the state's poppy trade. But officials say the midterm summer elections will still go on.