This paper aims at making explicit the micro foundations of the government's preference function in an influence-driven political economy model. It also addresses the behavior functions of domestic and foreign firms in their attempts to gain policy favors. These favors are granted by means of subsidies. In our model, the government simultaneously chooses three interdependent policy instruments under the political influence of domestic and foreign firms. Thus, we create a political market characterized by utility-maximizing and profit-maximizing behaviors of its actors, which takes place in a computable general equilibrium model. Endowed with these features, this model fills a gap in the literature. However, our results demonstrate that the model is only valid under a reasonable set of constraints on its parameters. Finally, this paper formally shows the key role of the subsidy elasticity of political cost in limiting the distortions created by the influence of interest groups.