Answer
Aníbal Cavaco Silva was the president to whom Sócrates submitted his resignation. Cavaco Silva was the president of Portugal from 2006 to 2016. He is a member of the Social Democratic Party. Sócrates was the prime minister of Portugal from 2005 to 2011. He is a member of the Socialist Party. Sócrates submitted his resignation in 2011 after his government was defeated in a vote of no confidence.