The party congress held January 18, 1920 resolved that the party would contest the 1920 Czechoslovak National Assembly election independently. The party contested the Chamber of Deputies election in the Nové Zámky 16th electoral district and the Košice 20th electoral district. However, the party contested the Senate election on a joint list with the Czechoslovak Social Democratic Workers Party. The election campaign was initiated in March 1920. On March 16, 1920 a brief general strike was organized in Bratislava, to support socialist demands after the elections. Banners with slogans like "Death to profiteers" and "Long live communism" were put up in the city. The party got 1.8% of the votes in Czechoslovakia. The main stronghold of the party was the Nové Zámkyelectoral district. In the Nové Zámky constituency, the party won 35.7% of the National Assembly vote. It mustered 110,282 votes in the constituency, winning four seat in the National Assembly. Paul Wittich, who had been the chairman of the Pressburg Workers Council, became the chairman of the parliamentary faction of the party. The three other parliamentarians of the party were Samuel Mayer, Dr. Jószef Földessy and Gyula Nagy. Wittich, Mayer and Nagy were elected from Bratislava, whilst Földessy was elected from Komárno. The party also won two seats in the Czechoslovak Senate from Bratislava, represented by Matthias Kreppenhofer and Antal Svrak.
Press
The Hungarian section of the party published a weekly newspaper, Népszava, whilst the German organ was Volksstimme.
The socialist movement in Bratislava was radicalized, as Hungarian revolutionaries settled in Czechoslovakia in large numbers. A party meeting was held on July 11 and 18, 1920. The meeting approved a proposal by F. Pfifferling to adhere to the Communist International. Népszava and Volksstimme became pro-communist organs. Wittich, who had denounced the Hungarian Soviet Republic at the meeting, was deposed from his leadership position. A party congress was convened on September 24, 1920, at which the old leadership was expelled. The Marxist grouping eventually merged with the Communist Party of Czechoslovakia. The social democratic minority re-organized themselves. In October 1920, they launched new newspapers in German and Hungarian. On November 20, 1920, a German Social Democratic Party was formed, and on December 4, 1920 the small group of Hungarian social democrats that hadn't joined the communists formed the Hungarian Social Democratic Party. The Hungarian-German party thus consisted of two national sections. However, starting from the end of 1920 members of the German section of the party began defecting to the German Social Democratic Workers Party in the Czechoslovak Republic. The two German parliamentarians, Wittich and Mayer, were amongst those who left the party in late 1920. As of 1926 the German section had been completely absorbed by DSAP. On January 1, 1927 the Hungarian remainder of the party merged into the Czechoslovak Social Democratic Workers Party, becoming a Hungarian section of the Czechoslovak party.
