Answer
In 1955, Mátyás Rákosi forced Nagy out of the government. Rákosi had been the leader of Hungary since 1948, and he was a staunch Stalinist. Nagy was a more moderate communist, and he had disagreed with Rákosi on several issues, including the collectivization of agriculture. Rákosi eventually decided that Nagy was a threat to his power, and he forced him out of the government.