It also reminds me of the early Roman republic. The Romans had a three per party and the body that was the comitia centuriata (which was the popular assembly but originally in Rome those in the assembly also served as citizen as soldiers) was one of the bodies that passed laws and the only body that could vote for higher magistrates like the Consul, Praetor and Censor and the only way to become a high ranking magistrate was to have had some sort of command in the legions prior.