I like John Berger's synthesis of the role of the PRI in the history of twentieth-century Mexico:
And so I come to the point. The ravine between the vast field of broken promises and the popular expectations of more justice had somehow to be filled in, and the main political parties, beginning with the PRI (Party of the Institution of Revolution!), have carried this out for seventy years by making rubble of what had once been a political language. Broken promises, broken premises, broken propositions, broken laws. Every principle — except that of self-interest — was emptied of meaning.