 In 1946, Pérez joined the newly established Liberal Party, which obtained a congressional majority in the House of Representatives in the 1946 general elections.He was elected Speaker of the House of Representatives when the 1st Congress of the Philippines convened later that year, and would serve as House Speaker throughout the 1st and 2nd Congresses.Pérez was a leading congressional ally of Presidents Manuel Roxas and Elpidio Quirino, both of whom were Liberals.