United Socialist Organization a leftist alliance in West Bengal, India formed ahead of the 1952 Indian general elections. USO comprised of All India Forward Bloc, Socialist Republican Party , Bolshevik Party of India , Indian National Army, People's Movement and others and independents. USO came to an understand with Communist Party of India to form a anti-Congress front. Attempts were made to involve RSP in this front, but the negotiations ahead of the elections failed. Attempts were also made to reach agreements with Kisan Mazdoor Praja Party and Socialist Party of India, but no agreement was possible.

In total USO fielded 72 candidates in the West Bengal assembly and CPI 71. For the Lok Sabha USO fielded 8 candidates and CPI 9. In two constituencies the front supported RSP candidates. In other constituencies the front and RSP were in contest. In constituencies where there was no front candidate, the front appealed to voters to cast their vote for KMPP or the Socialist Party.

After the election, RSP joined the front.