Migration-regime liberalization and social security

"The pay-as-you-go social security system, increasingly burdened by dwindling labor force, can benefit from immigrants whose birth rates exceed those of the native born birth. The paper examines adynamic political-economy mechanism through which the social security system influences the young decisive voter's attitudes in favor of a more liberal immigration regime. A Markov equilibrium with social security consists of a more liberal migration policy, than a corresponding equilibrium with no social security. Thus, the social security system effectively provides an incentive to liberalize migration policy through a political-economy mechanism"--National Bureau of Economic Research web site.