RESUMEN
Why do veto players, under situations of divided government, often fail to acquiesce to policy changes that they ideologically prefer to the status quo? This paper proposes a political explanation for the variation in the emergence of these socially undesirable outcomes across systems with separation of powers. We show analytically that when the principle of separation of purpose is violated (i.e. when citizens cannot distinguish between the actions of the different branches of government), veto players might develop an incentive to block Pareto-improving reforms. We illustrate our argument by comparing the divergent contemporary experiences of two Latin American countries with divided government: Mexico and Brazil. While in Brazil the lack of strong parties has allowed separtion of purpose to develop, thus preventing socially inefficient policy gridlock from emerging, the strong institutionalization of Mexican parties has made veto players in this country to develop incentives to block reforms ideologically favored by all relevant political actors.