Cuba has had a communist political system since 1959 based on the "one state – one party" principle. Cuba is constitutionally defined as a Marxist–Leninist socialist state guided in part by the political ideas of Karl Marx, one of the fathers of historical materialism, Friedrich Engels and Vladimir Lenin. Despite being regarded as a Communist state, the ideology of José Martí is what serves as the main source of influence in Cuban politics. The present Constitution, which was passed in a 2019 referendum, also describes the role of the Communist Party of Cuba to be the "leading force of society and of the state" and as such has the capability of setting national policy. The 2019 Constitution identifies the ideals represented by Cuban independence hero José Martí and revolutionary leader Fid