Entering the Hungarian Parliament in 1886, Tisza became a leader of the Liberal Party (led by his father, Kálmán Tisza (Tisza, Kálmán)) and a defender of the dual monarchy and of Hungary's large landed interests. He became prime minister in 1903 but was heavily defeated at the polls in 1905. He served as president of the lower house from 1912 and was again prime minister from June 1913. In July 1914 Tisza initially resisted the view that Austria-Hungary should declare war on Serbia; he agreed to support the war only if Austria-Hungary would not annex further Slav territory (he regarded an increase in Slav subjects as a danger to the dualist system). Tisza resigned in protest over the new emperor Charles I's (Hungarian king Charles IV's) decree for suffrage reform in Hungary (June 15, 1917). Held responsible for provoking the war and for his country's suffering during World War I, Tisza was assassinated shortly before the end of the war by Magyar leftists.