Collective leadership was introduced following Stalin's death in 1953 and subsequent party leaders ruled as part of a collective. First Secretary Nikita Khrushchev criticized Stalin's dictatorial rule at the 20th Party Congress, but his increasingly erratic decisions lead to his ouster in 1964. He was replaced in his posts by Leonid Brezhnev as First Secretary and by Alexei Kosygin as Premier. Though Brezhnev gained more and more prominence over his colleagues, he retained the Politburo's support by consulting its members on all policies. Collective leadership was maintained under Yuri Andropov and Konstantin Chernenko. Mikhail Gorbachev's reforms espoused open discussion, leading to members of the leadership openly disagreeing on how little or how much reform was needed to rejuvenate the Soviet system.