Ahead of new elections in 1963, Contín was nominated as the UCRP candidate for governor of his province in a ticket with the Mayor of Concepción del Uruguay, Teodoro Marco.

His government had no majority in the provincial House of Representatives, but was able to enact significant initiatives largely due to the skill of the UCRP caucus leader, César Jaroslavsky.

[2][3] Overthrown, as was a fellow UCRP leader, President Arturo Illia, by the self-styled Revolución Argentina coup in 1966, Contin continued to be active in his party, which had retaken control of the UCR through the leadership of Ricardo Balbín.

Contín, however, lost support from the majority of UCR delegates, who shifted towards the center-left leader of the "Movement for Renewal and Change" faction, Raúl Alfonsín.

Alfonsín had been among the few political figures of any party to publicly oppose the ill-conceived invasion, and succeeded Contín as president of the National Committee of the UCR.