Most magistracies were elective (except for the position of
dictator). None was assigned by lot. The people, assembled in tribes,
elected the lower magistrates and the tribunes of the plebs. The
people also appointed the higher magistrates (consuls, praetors,
censors) when assembled in centuries. So it is possible to say,
simplifying a complex system that changed and developed during the republican period, that in Rome the people elected the magistrates
but could not themselves be magistrates. Since the census was
regularly revised, social and political mobility was possible from
generation to generation. The descendants of citizens belonging to
the lower census categories could accede to magistracies if their
wealth and status had increased sufficiently. However, at any given
moment, the only power enjoyed by the lower classes was that of
choosing among candidates from the upper classes.