He was elected Senator of the Republic in the period 1963–1968, under the first government of the architect Fernando Belaunde Terry, who also appointed him Minister of Foreign Relations ( from July 28, 1963 to September 15, 1965), in his first ministerial cabinet, chaired by Óscar Trelles.

Censored this, Schwalb replaced him in the presidency of the Council of Ministers (from December 31, 1963 to September 15, 1965), maintaining the portfolio of Foreign Relations.

He supported his Popular Action party in the campaign in favor of democratic restoration and ran for the first vice presidency in the formula headed by Belaunde, who triumphed for the second time in the general elections of 1980.

Faced with the resignation of the cabinet chaired by Manuel Ulloa Elías, motivated by attrition, Schwalb was summoned to preside over the Council of Ministers and assume the Foreign Relations portfolio (from January 3, 1983 to April 10, 1984).

Later, he was ambassador on a special mission to the United States and Canada, as a result of the border conflict between Peru and Ecuador in 1995.