 The reign of the first four kings was distinct from that of the last three kings . The first kings were elected . Between the reigns of the final three kings , however , the monarchy became hereditary , and as such , the senate became subordinated to the king . This breach in the senate 's sovereignty , rather than an intolerable tyranny , was probably what led the Patricians in the senate to overthrow the last king . The king may have sought the support of the Plebeians ; however , the Plebeians were no doubt exhausted from their continued military service , and from their forced labor in the construction of public works . They were probably also embittered by their lack of political power , and therefore did not come to the aide of either the king or the senate . 
