The credibility of Mexico City's left-wing mayor, Andres Lopez Obrador, as a contender in next year's election for the presidency of Mexico grows stronger by the day. And it is his enemies who have so far proven to be his most bankable asset. Obrador, who will almost certainly be the presidential nominee of the leftist Demo-cratic Revolutionary Party, is a charismatic populist who has a solid base of support among both the urban masses and the rural campesinos, both of which groups remain marginalized and largely cut off from the prosperity of the middle and upper classes. However, it was...