Theoretical foundations: The gap between parties and movements

The aim of the following research note is to review the latest scholarly contributions on a specific and relatively underexplored trend in the transformation of political parties: movementization, defined as the process of transformation undergone by parties as they incorporate organizational, strategic and discursive repertoires of social movements (Della Porta et al., Reference Della Porta, Fernández, Kouki and Mosca2017). This note seeks to fill the gap between studies on political parties and social movements while also proposing new research perspectives.

Above all, political parties and social movements are crucial actors of representative democracies. Although they have different roles and features, they can interact with each other in many ways (Caiani and Csiar, Reference Caiani and Csiar2018). However, the relationship between parties and movements has recently been underestimated by scholars and often framed in terms of opposition, with each occupying distinct spheres of political action. While earlier scholarship did include important qualitative and historical approaches to political parties, and quantitative methods have also long been present in studies of social movements—particularly in network analysis—the fields have, over time, increasingly diverged in both focus and methodology. This differentiation, more pronounced in recent decades, has contributed to a relative separation: party politics has tended toward quantitative analysis, whereas movement studies have often prioritized qualitative approaches (Tarrow, Reference Tarrow2021, p. 12). This division can be seen as a form of self-limitation within each field rather than a reflection of inherent methodological divisions.

More broadly, parties have been primarily studied by political scientists and are seen as organizations identified by an official label that run in elections and can place candidates in public offices (Sartori, Reference Sartori1976). However, their forms are not regarded as historically fixed; instead, they evolve over time, appearing to oscillate between the domains of society and the state (Duverger, Reference Duverger1954). Parties first emerged in representative democracies as organizations of notables, in the late 19^th century, they had no direct presence in society and operated exclusively within institutions such as parliaments. This era is therefore referred to in party scholarship as “parliamentarism” (Manin, Reference Manin1995) because of parties’ exclusive intra-moenia activity. At the beginning of the 20^th century, mass parties developed in response to the expansion of universal male suffrage and the introduction of proportional electoral systems, allowing the newly enfranchised masses to gain political representation. These parties established a strong grassroots presence, organizing through local branches. Following the “golden age” of political parties, mass party organizations began to decline in the face of profound socio- economic and political changes—such as the erosion of class-based identities (Franklin, Reference Franklin, Franklin, Mackie and Valen1992), the rise of post-materialist values (Inglehart, Reference Inglehart1977), and growing disengagement from traditional structures. In response, new organizational models emerged. Catch-all parties (Kirchheimer, Reference Kirchheimer1966) moved away from class-rooted mobilization strategies, broadening their appeal and weakening ideological commitments, while electoral-professional parties (Panebianco, Reference Panebianco1982) prioritized media- oriented campaigning and professionalized leadership over grassroots involvement. This evolution culminated in the rise of cartel-parties (Katz and Mair, Reference Katz and Mair1995), increasingly reliant on public funding and embedded within state institutions, thereby deepening the gap between parties and civil society. Many scholars have interpreted this trajectory as a broader “hollowing out” of party organizations (Cohen, Reference Cohen2019; Schlozman and Rosenfeld, Reference Schlozman and Rosenfeld2019). In turn, recent developments such as digitalization (Gerbaudo, Reference Gerbaudo2019) and movementization (Cervera-Marzal, Reference Cervera-Marzal2024) can be seen as strategic attempts to rebuild legitimacy and restore connections with disillusioned constituencies. In this context, social movements have played a crucial role in articulating grievances increasingly overlooked by mainstream parties, further reinforcing their function as alternative vehicles of political expression (Della Porta, Reference Della Porta2015).

Social movements, instead, have captured the interest of political sociologists and operate in the realm of contentious politics, mobilizing grassroots activism to challenge institutional power structures and articulate demands that often fall outside conventional political channels (McAdam et al., Reference McAdam, Tarrow and Tilly2001; Della Porta and Diani, Reference Della Porta and Diani2020). Scholars of social movements often point out that research on political parties has shifted its focus from the relationship between parties and society to a narrower emphasis on elections. At the same time, social movements have typically been framed as phenomena situated outside the sphere of political institutions (Tarrow, Reference Tarrow2021, p. 10). Consequently, these two fields have remained largely disconnected, showing little engagement with each other.

For decades, this divide has dominated scholarly debates, with limited attention to the interactions and overlaps between the two spheres. The well-documented crisis of political representation (Manin, Reference Manin1995) has further deepened the disconnection between institutions and society, and, by extension, between parties and movements (Della Porta, Reference Della Porta2015). Only when the boundaries between these actors began to blur some scholars started to explore their interrelations more systematically. As Tarrow (Reference Tarrow2021) notes, the ongoing crisis of parties is pushing Western democracies toward a “movement society,” where the distinction between parties and movements becomes increasingly porous. In this context, growing attention has been devoted to the reciprocal influences between social movements and party systems. Kitschelt (Reference Kitschelt1988), for instance, emphasized how left-libertarian parties in Europe emerged from movements and adopted participatory innovations rooted in those experiences.

Similarly, the theory of cycles of contention (McAdam et al., Reference McAdam, Tarrow and Tilly2001) illustrates how protest waves can generate openings for new political actors, linking movement dynamics with institutional change. These theoretical contributions have helped move beyond the rigid dichotomy between movements and parties, laying the groundwork for the study of hybrid formations such as movement-parties.

Indeed, studying the movementization of parties offers a valuable perspective for understanding an emerging and potentially transformative trajectory in party politics. In a context where parties face a legitimacy crisis, many of them appear to be increasingly inspired by social movements—forms of collective action that, conversely, are experiencing a growing role as channels of political participation. This phenomenon not only challenges established distinctions between institutional and non-institutional politics but also calls for a more systematic examination. Despite a growing interest in recent years, the literature on this topic remains fragmented and lacks conceptual clarity. This research note, aiming to map and organize existing contributions, could thus help consolidate this emerging field and provide a foundation for future research.

The rise of movement-parties: Definition and causes of emergence

Kitschelt (Reference Kitschelt, Katz and Crotty2006) offers one of the earliest definitions of movement-parties, focusing primarily on the rise of left-libertarian parties in Europe, such as green parties. These parties are particularly notable for their fluid, networked structures, which distinguish them from traditional political parties. They are also closely connected to environmental movements, highlighting their alternative approach to party organization. In his analysis, although with some significant differences compared to the Greens, he also includes the populist far-right parties that emerged in Europe in the 1980s and 1990s. He defines movement-parties as “coalitions of political activists that emerge from social movements and attempt to transfer the organizational and strategic practices of movements into the arena of party competition” (Kitschelt, Reference Kitschelt, Katz and Crotty2006, p. 280). More in depth, three different features seem to characterize these parties:

Firstly, movement-parties tend to reject traditional bureaucratic organization, investing minimally in formal structures. Membership is typically informal and based on participation in initiatives or assemblies, rather than official enrollment mechanisms.

Secondly, movement-parties seem to invest little in addressing social choice problems. They lack an institutionalized system for aggregating interests and making binding decisions. As a result, their policy platforms often concentrate on a limited range of salient issues, neglecting broader programmatic coherence. This reflects a wider trend in contemporary party politics: the declining structuring role of ideological frameworks and the emergence of additive programmatic visions (Lehrer and Lin, Reference Lehrer and Lin2019). Movement-parties exemplify this tendency by prioritizing responsiveness to grassroots demands over ideological consistency.

Thirdly, their main innovation lies in their hybrid nature: positioned between movements and parties, they simultaneously adopt the strategic logic of electoral competition and the action repertoire of contentious politics.

Important innovations also concern the decision-making practices within these new parties. Kitschelt identifies a process that can move between two extremes on an ideal continuum: on one hand, the vertical decisions made by the charismatic leader (far-right populist parties) and, on the other, bottom- up participatory democracy practices, typical of non-patrimonial networked parties (green parties). Regardless of the differences between the networked and patrimonial models, both types indicate an incomplete, volatile and not fully formalized decision-making process.

According to Kitschelt, certain conditions are necessary for these movement-parties to emerge:

1. 1. Emergence of Collective Interests and Mobilization: the existence of broad constituencies of individuals linked by common interests, who adopt extra-institutional and unconventional action practices.

2. 2. Existence of Neglected Issues: traditional parties often avoid addressing certain issues because they fear alienating segments of their electorate. As a result, these topics remain politically marginalized, creating space for new political actors to champion them.

3. 3. Favorable Electoral Conditions: weak presence of formal and informal barriers to entry (proportional systems and low thresholds can aid the emergence of new actors).

However, Kitschelt emphasizes the transient nature of movement-parties, challenging the idea of a linear evolution from movements to stable parties. Their hybrid character tends to persist only as long as the original issues driving mobilization remain salient. Once these fade—or as the party seeks broader electoral appeal or governmental roles—it is often compelled to expand its agenda and adopt more formalized structures. Electoral competition and institutional responsibilities thus push movement-parties toward organizational consolidation. For Kitschelt, this makes them relatively rare and short-lived phenomena in comparative perspective. Nonetheless, his work provides a foundational framework for understanding actors operating at the intersection of contentious and institutional politics, albeit with a skeptical view of their long-term viability.

As Kitschelt notes the rise of movement-parties is often tied to moments of profound political and economic crisis which reveal the structural weaknesses of traditional parties. The 2008 financial crisis represented a critical juncture that exposed the failures of neoliberal policies and deepened public disillusionment with mainstream parties especially in Southern Europe. In this context new actors such as SYRIZA in Greece and Podemos in Spain emerged from anti-austerity mobilizations channeling popular frustration into institutional politics (Mosca and Quaranta, Reference Mosca and Quaranta2017). Similarly, the Five Star Movement in Italy leveraged digital platforms to merge grassroots activism with electoral participation presenting itself as an alternative to the mainstream party system (Deseriis, Reference Deseriis2020a).

These parties capitalized on the erosion of traditional political cleavages—most notably the left–right divide—by framing their discourse around a populist opposition between “the people” and “the elites” drawing on Laclau's (Reference Laclau2005) notion of “populist reason.” This allowed them to build cross-class coalitions based on shared grievances rather than ideological coherence. Expanding on Kitschelt's (Reference Kitschelt, Katz and Crotty2006) framework Della Porta et al. (Reference Della Porta, Fernández, Kouki and Mosca2017) further identified additional conditions underpinning the rise of movement-parties.

1. 1. Transformation of Cleavage Structures: New political actors emerge when societal fractures, driven by unaddressed issues, lead to heightened inequalities.

2. 2. Favorable Electoral Conditions: Low entry thresholds, proportional systems, decentralization, and electoral volatility create favorable conditions for the rise of new parties.

3. 3. Crisis of Traditional Bipartisanship: Movement-parties rise when traditional parties face a crisis in representation and neglected key issues.

4. 4. Mobilization of Unrepresented Issues: Movement-parties adopt claims ignored by traditional parties, as seen during the 2008 crisis with movements like Indignados and Aganaktismenoi, focusing on issues like austerity.

5. 5. Anti-System Mass Mobilizations: These parties are closely linked to social movements that challenge the established system, evident in the protests after the 2008 crisis.

In summary, the movementization of political parties can be interpreted as a response to both short- term crises and long-term structural changes. Critical junctures—such as the 2008 crisis—have delegitimized traditional parties and opened space for new actors to articulate neglected grievances (Della Porta et al., Reference Della Porta, Fernández, Kouki and Mosca2017). At the same time, more enduring trends such as the organizational decline of parties (Schlozman and Rosenfeld, Reference Schlozman and Rosenfeld2019), the erosion of ideological coherence, and the rising influence of non-party actors (Tarrow, Reference Tarrow2021) might push parties to adopt movement-like features. Movementization, therefore, emerges as both a reactive and strategic adaptation to evolving political and societal conditions.

Key characteristics of movement-parties

Besides focusing on the causes of their emergence, the literature has also explored the characteristics of movement-parties, which are distinguished by their aim to integrate organizational, strategic and discursive repertoires derived from social movements (Della Porta et al., Reference Della Porta, Fernández, Kouki and Mosca2017, p. 23).

Organizationally, movement-parties tend to adopt participatory, networked structures that emphasize grassroots involvement and use digital platforms to foster decentralized decision-making. While they aim to challenge the bureaucratic rigidity of mainstream parties, they also display traits of leader-centered personalization.

Strategically, these parties have capitalized on widespread disenchantment with traditional politics, often making rapid transitions from street-level activism to parliamentary or even governmental roles. Their approach combines conventional electoral tactics with continued engagement in protests and direct action, allowing them to remain rooted in contentious politics while operating within institutions—a dual strategy that can, however, generate internal tensions as they assume governing responsibilities.

Discursively, movement-parties frame themselves as vehicles for bringing neglected social movement demands into institutional politics. Their narratives often focus on hope and democratic renewal, frequently adopting populist rhetoric that opposes a virtuous “people” to a corrupt “elite” (Mudde, Reference Mudde2004). In doing so, they challenge traditional cleavages and promote new divides centered on themes such as environmental sustainability, globalization, and social justice.

Beyond the left: Movementization across the political spectrum

While early studies on movement-parties mainly focused on left-wing actors, such as green parties (Kitschelt, Reference Kitschelt, Katz and Crotty2006) or anti-austerity parties (Della Porta et al., Reference Della Porta, Fernández, Kouki and Mosca2017), recent research instead highlights the ideological diversity of movementization. However, in his pioneering work, Kitschelt stated how, with some differences, some right-wing movement-parties could be placed in this category as well. They do not grow out of strong and disruptive social movements, as green parties. Instead, they may serve as substitutes for movements, preempting violence or protest by channeling grievances into party politics. These parties often adopt movement-party tactics, such as initiating disruptive protests against immigration or high taxes, but they don't always rely on grassroots participation. So, as Kitschelt said, they show movement-party appeal without movement support. Instead, many of those are led by a single charismatic leader who dominates the party. As in other movement-parties, their organizational structure tends to be fluid, lacking strong formal membership and marked by internal instability. Leadership tends to be highly centralized, with frequent splits and crises. Far-right parties like Germany's Alternative für Deutschland (AfD) and France's Rassemblement National (RN) have adopted these movement-like strategies, blending nativist populism with grassroots mobilization. Some recent works tried to develop this Kitschelt's framework of far-right movement-parties. Caiani and Csiar (Reference Caiani and Csiar2018), Pirro and Castelli Gattinara (Reference Pirro and Castelli Gattinara2018) argue that far-right movement-parties use protest tactics and anti-elite rhetoric to position themselves as challengers to the political establishment, much like their left-wing counterparts.

This ideological expansion underscores the strategic utility of movementization. Tarrow (Reference Tarrow, Meyer and Tarrow2018, Reference Tarrow2021) observes that even some traditional parties have integrated movement-like elements to energize their bases and adapt to changing voter expectations. In particular, the US Republican Party moved toward a movement-party model by capturing much of the energy of the Tea Party movement and then the far-right Trumpian movement. Similarly, the Democratic Party was influenced by a series of progressive movements based on race, gender, environment and sexual preference, and integrated these new constituencies (Tarrow, Reference Tarrow2021, p. 25). In the same way, in Britain, the Momentum movement sought to movementize and radicalize the Labour Party from inside, under the far-left leadership of Jeremy Corbyn (Avril, Reference Avril, Avril and Béliard2018; Prentoulis and Thomassen, Reference Prentoulis, Thomassen, Fominaya and Feenstra2019). Recently, Butzlaff (Reference Butzlaff2023) extends this argument, demonstrating that institutionalized parties in Austria, Germany and the UK are increasingly adopting movement-inspired organizational practices and discursive strategies. Similarly, Kim (Reference Kim2024) showed that contemporary movement-parties can be identified across the entire political spectrum, from the left to the center and the right.

Building on these gaps and recognizing that this trend is not confined to a specific party family, some scholars have sought to adopt a comparative perspective in examining movement-parties and movementization within political systems. In particular, Borbáth and Paxton (Reference Borbáth and Paxton2025) provide a comparative assessment of movement-parties in post-2008 Europe, developing a systematic typology based on three key dimensions: organizational investment, programmatic breadth, and protest mobilization. The authors argue that movement-parties, blending elements of social movements and political parties, exhibit significant heterogeneity across these dimensions. Their findings challenge Kitschelt's definition of movement-parties, demonstrating that only a small subset fits the ideal type of low organization, narrow programmatic focus, and high protest activity. Instead, they identify various subtypes on these three dimensions. The study highlights that movement-parties are not a monolithic category but rather a spectrum of political actors employing different strategic combinations of organization, issue focus, and mobilization. Their main contribution to the literature lies in their attempt to operationalize Kitschelt's definition in three dimensions, enabling the measurement and quantification of movementization across political systems. This approach facilitates comparative studies in the field, moving beyond solely relying on case studies, which have been characterizing this field for years. Moreover, the authors conclude that future research should move beyond a rigid definition of movement-parties and instead explore their dynamic nature and adaptation to different political contexts.

So, much evidence suggests that today a trend of movementization is emerging and this does not concern movement-parties and challengers only, but mainstream parties seem to try to incorporate some movement-like features in order to revitalize themselves. Moreover, while early studies on the topic focused primarily on Western Europe, more recent contributions emphasize that movementization is a global phenomenon, involving parties in diverse contexts including Eastern Europe (Caiani, Reference Caiani2021; Fiket et al., Reference Fiket, Pudar Drasko and Vasiljević2024), the US (Tarrow, Reference Tarrow2021), Latin America (Anria, Reference Anria2018), and Asia (Laohabut and McCargo, Reference Laohabut and McCargo2024).

Research gaps and future directions

Despite significant advances in the study of movement-parties, several gaps remain.

First, although the literature continues to identify and describe new cases of movement-parties worldwide, there is still no overarching theory of movementization that captures both its underlying causes and explanations on one hand, and its various manifestations across contexts and time on the other. As shown, existing research tends to focus on specific case studies or ideological clusters, limiting the ability to compare movementization systematically. The most significant risk of not having a general theory is that the concept could be stretched too far, leading to its overlap with other similar concepts such as populist, digital and platform parties (Gerbaudo, Reference Gerbaudo2019; Deseriis, Reference Deseriis2020b). This could result in a dilution of its meaning, making it difficult to distinguish between distinct political phenomena that share certain characteristics but differ in important ways.

Secondly, the lack of a standardized framework for measuring movementization limits comparative analysis, as most studies rely on qualitative methods. Yet, recent literature highlights how movementization extends beyond specific party families, suggesting the need for tools that enable systematic comparison. Borbáth and Paxton (Reference Borbáth and Paxton2025) take a first step by proposing a typology based on multiple quantitative datasets. Still, such efforts should be complemented by qualitative approaches capable of capturing movementization dynamics even within parties not typically classified as movement-parties.

In conclusion, the literature on movement-parties highlights their unique role as hybrids between contentious and institutional politics. From their emergence in response to crises of representation to their integration into diverse ideological contexts, movement-parties challenge traditional notions of party politics. However, movementization does not involve movement-parties only, but it seems to become a general trend of political parties across systems. So, the trajectories of movementization and its broader implications for democratic systems remain an open field for further exploration. Developing tools to measure and compare movementization across parties is a critical next step in advancing this research agenda.