Yrigoyen's fractious opposition, which together continued to enjoy a majority in the Upper House, appointed Melo Provisional President of the Senate in the same year.

[2] He secured his party's nominatation for the presidency ahead of the 1928 election, though voters' support for the state oil concern established by Yrigoyen during his first term, YPF, and nostalgia for the aging leader himself translated into a landslide defeat for Melo and his running-mate, Vicente Gallo.

Under his aegis the special branch of the Federal Police was created, implementing a policy of systematic torture of opposition figures.

In 1939, he was named representative to the Pan-American Union, where he participated in a mutual defense treaty entered into by the United States and most of the other nations of the Americas in 1940 as a response to World War II.

Melo retired from politics and continued to teach commercial and maritime law; he died in the seaside resort city of Pinamar in 1951.