Here are the results from a recent poll on vote intention in Mexico City, in today's El Universal (direct link to detailed PFD here). Notably, for the PRD, which leads in party intention with 26 percent, in every imaginable scenario (the paper lists an amazing 10 options), PAN leads in none, with the PRD and PRI coming on top in respective candidate scenarios.
A consistent vote winner: PRI's ex-president Beatriz Paredes Rangel. Will the 2012 PRI formula be Peña Nieto-Paredes? Much caution nonetheless: At this point, of course, polls more than anything reflect merely name recognition.