The article examines the key criteria for the concept of the dominant party, such as its ability to consistently and steadily win the elections, the significant duration of its stay in power, as well as its personnel control of the Cabinet of ministers. In the sociopolitical discourse the dominant party enjoys a privileged ideological position and has more opportunities compared to its competitors to appeal to voters. Along with that the party dominance reveals itself not only in its external manifestation (the stay in power), but also in the substantial one – the ability to exercise an effective political choice. The article analyzes the factors of sustainability of the dominant party systems: the historical merits of the dominant party; the ruling party’s ability to effectively take advantage of the electoral system; its strong relationships with the most affluent social groups and major corporations, as well as with the predominant ethnic or linguistic social groups; a privileged access of the ruling party to media resources. These factors are also effective in the polycentric political systems without any dominant party. However, under the dominant party systems they manifest themselves in a complex way, providing the ruling camp with a multi-layered protection due to a synergy effect. Particular attention is paid to the phenomenon of clientelism, widely used by the ruling party as a strategy of political mobilization. While the scope and durability of the pork-barrel politics make this phenomenon socially significant and, accordingly, subject to public control, clientelism complies with the standards of democratic process, even in spite of its possible negative effects on the public good. However, if discrimination arose by clientelism reaches the level that denies clients the right to choose, this is certainly not consistent with the rules of democracy.