How does mass partisanship develop where it does not already exist – particularly in countries like Brazil that lack deep socioeconomic or cultural cleavages? And why in some cases does identification with a particular party subsequently weaken? In this chapter we explain the spread of petismo, and examine its recent decline.

As suggested, explaining the rise of petismo is not easy, given Brazil's cultural and institutional context. It might seem easier to explain petismo's decline – after all, the PT was in power during a deep political and economic crises in 2013. However, we just noted in Chapter 3 that because partisanship can be a relatively “sticky” psychological attachment, it can shape perceptions of government performance. If this is true, how then to explain the weakening of partisan attachments?

Petismo's growth from none to about one in four voters in a relatively short time period is a remarkable achievement – for any party, in any country. It is also theoretically puzzling. Scholars believe Brazil is infertile terrain for planting the seeds of partisanship, given its comparatively shallow social cleavages (Mainwaring & Scully 1995a). Its political institutions also work against the emergence of mass partisanship: the electoral rules foster high party-system fragmentation and intraparty competition, which enhance the importance of individual candidates’ reputations, complicate voters’ efforts to understand where parties stand on the issues, and limit the relevance of party labels as “cues” (e.g., Mainwaring 1999; Samuels 1999; Ames 2001).

When social cleavages cannot explain the emergence of mass partisanship from the “bottom up,” scholars turn to political elites’ efforts from the “top down.” At first glance this approach also appears to explain less rather than more. After all, leaders of all of Brazil's main parties – including the PT – chose to converge on the political center since 2000, diluting the coherence of their programmatic positions. Lupu (2013) predicts that diluting a party's “brand” can lead to a collapse of party ID, but that only makes the PT's success up through 2013 even more puzzling.

To understand the rise of petismo we focus on the PT's organizational strategy,which differed from other parties’. Scholars taking a “top-down” approach to explaining the emergence of partisanship have considered variation in national-level party organizations, comparing and contrasting “elite” and “mass” parties, for example. We show that local-level party institutions should be included in the story of how parties cultivate affective ties.