as the Action Committee of the Left () and opted for the unified social-democratic party with the SSDP and the SDPBH. Soon afterwards, the Vojvodina social-democrats reversed their decision. The Unification congress of the Socialist Labor Party of Yugoslavia (Communists) (, SRPJ(k)) was held in Belgrade on 20–23 April 1919 as consolidation on the left of the political spectrum. The new party was joined by the SSDP en masse, and by independent leftists who splintered away from various nationalist youth organisations and social democratic parties. The Labour Socialist Party of Slovenia () split from the JSDS and joined the SRPJ(k) on 13 April 1920. Clashes continued within the party between leftists and centrists – the latter favouring pursuit of reforms through a parliamentary system. The leftist faction prevailed at the second congress held in Vukovar on 20–24 June 1920 and adopted a new statute. That aligned the party entirely with the Communist International (Comintern), implementing all instructions received from the Comintern. Furthermore, the party was renamed the Communist Party of Yugoslavia (, KPJ) to allow its membership in the Comintern. Filip Filipović and Sima Marković, both former SSDP activists, were elected to lead the KPJ. By May 1920, the KPJ had about 50,000 members, and numerous sympathisers largely drawn from among 300,000 members of trade unions and youth organisations. 1920 Elections and ban In the 1920 Constitutional Assembly election, the KPJ won 58 out of 419 seats. The best results were achieved in large cities, in Montenegro and Macedonia as a result of protest votes against the regime on account of past or expected actions coming from unemployed urban voters and from voters in regions having no other attractive national or regional opposition parties found in the Slovene lands, Croatia-Slavonia, and Bosnia and Herzegovina. In light of difficult economic and social circumstances, the regime viewed the KPJ as the main threat to the system of government. In response to the KPJ's electoral success at the local and regional level including Belgrade and Zagreb earlier that year in March–August, and at the national level the Democratic Party and the People's Radical Party advocated prohibition of communist activity. The regime saw the KPJ as the greatest impediment to realisation of views held by King Peter I on resolution of Serbian national question. In December 1920, KPJ-led miner strikes in Slovenia and Bosnia and Herzegovina led to suppression by the royal army and