Coesão e Disciplina Partidária no Senado Federal

This article analyzes party discipline in the Brazilian Senate based on a previously untapped database covering roll call votes from 1989 to 2009. As occurs in the Chamber of Deputies, political parties in the Senate display a high degree of unity that remains reasonably stable over time. Despite the similar results in the two Houses, I suggest that the explanations are not the same. As compared to the Chamber of Deputies, the Senate appears to feel less power from the Executive, the leaders are scarcely relevant, and the decision-making process is less centralized. I do not offer a solution to this paradox, but I do suggest that it involves not only the institutional rules, but also the organizational characteristics and even the political profile of the Senators themselves