Party Switching in Elected Upper Chambers: The Case of the Brazilian Senate

Party switching has received considerable attention in academic literature in recent years, especially in Brazil. Surprisingly, however, very little is known about the reasons why senators decide to change their party affiliation. Against this backdrop, this study takes the first step and sheds light on the matter by investigating what is behind senatorial party defection in Brazil. Overall, the results indicate that ideological distance between senators and parties emerges as the primary factor explaining the switch, although this relationship is slightly conditioned by office and vote considerations. However, the findings also highlight how the behaviour of senators changes according to the degree of the seats up to contest in the upcoming elections (i.e. one-third or two-thirds of the chamber). Thus, our results add another piece to understanding the party switching puzzle in Brazil and bring important implications for legislative studies and legislative behaviour.