The few independent-minded Social Democrats who had not been sidelined by Communist salami tactics were pushed out in short order after the merger, leaving the party as essentially the MKP under a new name.

Its leader was Mátyás Rákosi until 1956, then Ernő Gerő in the same year for three months, and eventually János Kádár until the party's dissolution.

The new government of Nagy declared to assess the uprising not as counter-revolutionary but as a "great, national and democratic event" and to dissolve State Security Police (ÁVH).

Hungary's declaration to become neutral and to exit the Warsaw Pact caused the second Soviet intervention on 4 November 1956.

After 8 November 1956, the MSZMP, under Kádár's leadership, fully supported the Soviet Union.