The chief rival of Stamboliyski's BZNS was the Bulgarian Communist Party (BKP). After World War I the BZNS and BKP were the two leading parties in Bulgarian politics. Though the BZNS initially beat the Communist Party for political power, its authority quickly began to wane because, according to the communists, the BZNS wavered in its support between the proletariat and the bourgeoisie. Despite the fact that most of them were not rich, peasants still participated in an old bourgeois economic system, which was, from the Communist point of view, destined to fail.