The McCarthy Cold War era had taken a heavy toll on the Communist Party USA, as many American members were called to testify to congressional committees. In addition, due to the Soviet invasion of Hungary in 1956, many members became disenchanted and left the party. They were also moved by the Soviet leader Nikita Khrushchev's dismissal of Stalinism. In the United States, the rise of the New Left and the Warsaw Pact invasion of Czechoslovakia in 1968 created hostility between leftists and the CPUSA, marginalizing it.