 On April 19, 1933, together with Oscar Schnake, Salvador Allende, and Carlos Alberto Martínez, Grove founded the Socialist Party of Chile.He became General Secretary of that party in 1938 and president of the Popular Front coalition that won the presidential election that same year with the candidate Pedro Aguirre Cerda.Grove was elected Senator on May 9, 1934, in a by-election held to replace deceased Senator Eugenio Matte Hurtado, who had died in January of that year.