In 1975 a new constitution was promulgated to establish Greece as a republic with a political structure modelled on that of France. The constitution invested great power in the president, who is obligated to choose as prime minister the leader of the party gaining the most seats in parliamentary elections. Until the constitution was amended in 1986, the president could veto legislation, dissolve parliament, and call for a direct vote of no confidence in parliament. The sharp escalation of executive authority was controversial, but Karamanlis declared strong presidential powers necessary to deal with extraordinary episodes of Greece's political conflict. The five-year administration of Konstantinos Tsatsos, the first president under the new constitution, passed without his using the considerable powers that had been given to his office.