Montini and Angelo Roncalli were considered to be friends, but when Roncalli, as Pope John XXIII announced a new Ecumenical Council, Cardinal Montini reacted with disbelief and said to Giulio Bevilacqua: "This old boy does not know what a hornets nest he is stirring up." He was appointed to the Central Preparatory Commission in 1961. During the Council, his friend Pope John XXIII asked him to live in the Vatican. He was a member of the Commission for Extraordinary Affairs but did not engage himself much into the floor debates on various issues. His main advisor was Monsignore Giovanni Colombo, whom he later appointed to be his successor in Milan The Commission was greatly overshadowed by the insistence of John XXIII to have the Council complete all its work in one single session before Christmas 1962, to the 400th anniversary of the Council of Trent, an insistence which may have also been influenced by the Pope's recent knowledge that he had cancer.

What group did Montini oppose reforming?