1) The PAN and the PRD in Mexico State, as well as on the national level, have voted to "explore" a possible common candidate for Mexico State governor. None, however, has been decided upon yet; indeed, the coalition itself has not been set in stone.
2) AMLO, however, has already decided that no matter what, he will present his own candidate, which of course will split the left's vote and favor Peña Nieto, without even bother to wait for the official campaign period to start. Those pesky rules simply do not apply to him; he has already barnstormed every municipality in Mexico State and will now do it again, to back his candidate - in the fullest possessive meaning of the word.
3) There was no internal primary or vote among AMLO's followers; Polevnsky was simply "decided upon" in what appears to have been a commissioned opinion poll among the general electorate, though I am not sure about this yet. In any regard, the fact that the candidate's program, the "10 Commitments," was already drawn up and decided by AMLO before the candidate was elected, speaks volumes: Polevnsky is a pure figurehead whose own, and minimal, qualifications do not matter at all: The candidate could have been Winnie the Pooh as long as he had pledged allegiance to AMLO's program and pulled ahead in the polls, and this process has only served to highlight and not obscure this.
With these considerations in mind: I hope that Mexico State's voters see AMLO's conception of representative democracy for what it is: Hollow, plebiscitarian, and top-down.