Oil and politics have always been a volatile mix in Mexico, dating from the nationalization of the country's oil industry in 1938. The idea behind that revolutionary move was to wrest control of this rich national patrimony from foreign oil companies in order to better preserve it for the benefit of the Mexican people.

Since then, any talk of involving foreign companies in Mexico's oil business has been political hemlock. For many years, oil production has reliably served as the country's major source of revenue, and Pemex, the national oil monopoly, has been both a major employer and a major source of political patronage. Over the years, too, there has been vigorous debate about how — and how equitably — Mexico's petrodollars have been distributed; but the prominent place of oil in Mexico's national asset base has been a given.