In October 2017, Santana Lopes announced the intention to run again for the leadership of the Social Democratic Party. He resigned leadership of Santa Casa da Misericórdia de Lisboa in order to do so, but was defeated by Rui Rio. After the internal election, both Rio and Santana tried to cooperate on several levels within the party, an effort which was not successful from Santana's point of view. He grew increasingly disgruntled with the course of action imposed by Rui Rio, and in June 2018 he announced he would be ending his 42 years of party membership and would seek to create a new political party.