This thesis investigates the history of one of the longest-lived political parties in our party system, the Party of the Brazilian Democratic Movement (PMDB). From a national and diachronic perspective, we analyze its internal history covering more than two decades, from 1979 to 2002, in order to understand how the party moved from the protagonism to the background of national politics, but remaining yet as a determining actor in our political system. Taking into account the weight that the governing bodies have in defining the directions of the Brazilian political parties, as well as the strong presence of parliamentarians in these bodies with regard to the PMDB (Ribeiro, 2014), we use the concept of ruling coalition of Panebianco (2005) to analyze the party in central office (Katz and Mair, 1993) and argue that the understanding of the internal dynamics of its main governing bodies contributes to understanding the changes in the political and electoral strategies adopted by the PMDB, especially regarding the presidential elections. In order to achieve this goal, the thesis is based on a wide documentary investigation and on in-depth interviews with important politicians to the history of the party in their states, a pioneering effort in the studies related to this object. In this sense, this study is divided into two parts. The first one investigates the time period from 1979 to 1988, a moment in which the internal transformations of the party were more linked to the constant flow of politicians in and out of it. This period includes, among other events, the refoundation of the party in 1979, the incorporation of the Popular Party in 1982, the entry of José Sarney in 1985, the legalization of the communist parties in 1985 and the formation of the PSDB in 1988. On the other hand, in the second part of this study we investigate the time period from 1989 to 2002. In this second period, the internal transformations in the ruling coalition and consequently the electoral strategies adopted were more related to internal disputes between its different wings. Included in this period were the brief Ulyssist and Quercist hegemonies, which led Ulysses Guimarães and Orestes Quércia to be the presidential candidates respectively in 1989 and 1994, the indefiniteness in launching their own candidacy or joining with another party in the 1998 presidential elections and, finally the arrival of Michel Temer to the presidency of the party in 2001, consolidating the wing called "governists" as the party's ruling coalition thereafter. We suggest that the in depth study of this particular party, given the size and complexity of the PMDB, allow us an understanding of processes and dynamics that go beyond it. His study provides a view, from a specific point of view, of Brazil's political history during and after the democratic transition, and also allows us to shed light on other aspects of our politicalparty system, such as the dynamics of bipolarisation of the presidential elections in the country between PT and PSDB candidacies, whic...