 Norton de Matos returned to teaching, accepting a position as professor at the Instituto Superior Técnico, but was dismissed from his chair.He then became a leading opposition figure against the Salazar regime.In 1943, he was named to the National Council of Movement of National Antifascist Unity, or MUNAF, and on his 81st birthday, he was named the candidate of the opposition now united under the Movement of Democratic Unity (MUD, the successor organization to the MUNAF after 1945) for President in the election of 1949, under the dictatorial Estado Novo regime, while demanding freedom to advertise his message and the close inspection of votes.