After the war, Kallio was imprisoned for political reasons, but escaped from prison to Sweden. From 1920, Kallio was a member of the
Communist Party of Finland (SKP) and in 1921 he studied illegally at SKP propagandists' courses in St. Petersburg. Kallio returned to Finland in 1921, completed his military service in Vaasa in 1922–1923, and then worked as a carpenter in Pietarsaari. Kallio was a Socialist Workers' Party of Finland member of parliament in 1929–1930, representing the northern electoral district of
Vaasa Province. Kallio was arrested for distributing communist literature and was imprisoned again in 1930, when his term as a member of parliament ended. Kallio was also a
Pietarsaari city councilor and a member of SKP's Pietarsaari district committee and the representative board of Osuusliike Varma. ==Exile, purge and rehabilitation==