The Marxist aspect of the political economy approach offers a critical lens through which to analyze comparative politics, emphasizing the fundamental role of economic structures and class relations in shaping political outcomes. Rooted in historical materialism, this perspective posits that the economic 'base' (modes of production, class struggle) largely determines the political and ideological 'superstructure' (state, law, culture).

In comparative politics, the Marxist approach directs attention to how different states and political systems are shaped by their underlying economic systems. It examines the state not as a neutral arbiter but as an instrument of the dominant economic class, designed to maintain and reproduce capitalist relations. This leads to an analysis of class conflict, exploitation, and the ways in which economic power translates into political power across various national contexts. Key concepts include dependency theory, which explains underdevelopment in the Global South as a result of its integration into a global capitalist system dominated by core capitalist states, and world-systems theory, which views the global economy as a single, integrated system of core, semi-periphery, and periphery nations.

However, the Marxist approach faces several criticisms. It is often accused of economic determinism, oversimplifying complex political phenomena by reducing them solely to economic factors. Critics argue that it underestimates the autonomy of the state, the influence of non-class factors (e.g., ethnicity, religion, gender), and the role of ideology and culture in shaping political behavior. Furthermore, the adaptability of capitalism and the rise of welfare states in some contexts challenge the prediction of inevitable class polarization and revolution. The collapse of state-socialist regimes also raised questions about the practical application of Marxist theory.

Despite these critiques, the Marxist political economy approach remains invaluable for highlighting power imbalances, structural inequalities, and the often-hidden economic interests that underpin political decisions. It compels comparative political scientists to look beyond superficial political differences and examine the deeper material conditions that shape societies, providing a powerful framework for understanding global capitalism's impact on national politics and development.