A member of the Radical Civic Union ("Unión Cívica Radical", UCR) under the leadership of Leandro Alem, de la Torre abandoned the party in 1897 due to disagreement with the new leader, Hipólito Yrigoyen. Later, in 1908, he was part of the founding group of the Southern League ("Liga del Sur"), a local party. In 1911 he was elected for the provincial legislature representing the San Lorenzo Department; in 1912 he became a representative of Santa Fe ("diputado") for the Southern League in the lower house of the National Congress.