On 15 November 1945, as leader of the Smallholders' Party, the largest Hungarian political party, Kovács was appointed minister of agriculture in the Ferenc Nagy government. In February 1946 Kovács resigned to dedicate more time to the Smallholders' Party, of which he was now leader. Fearing the strength of this party and Kovács's influence, Soviet authorities arrested him on 25 February 1947 and charged him with plotting against the Soviet occupational forces. Without benefit of trial, he was sentenced to life imprisonment in Siberia.
In the autumn of 1955 Kovács was moved to Hungary, but he was not released until the spring of 1956. In the brief reform government of Imre Nagy, Kovács served as minister of agriculture and deputy prime minister (2–4 November 1956). On 3 November 1956, he was elected chairman of the reorganized Smallholders' Party. In 1958 he won a seat in parliament. Within weeks of his election, however, he became seriously ill and was never seated in parliament. Kovács died on 21 June 1959 in Pécs.
Max, Stanley M. The United States, Great Britain, and the Sovietization of Hungary, 1945–1948. Boulder, CO: East European Monographs, Distributed by Columbia University Press, 1985.