Kazasov took active part in the 1923 coup d'état and from 1923 to 1924 he was minister of the railways, post offices and telegraphs. In 1926 he was expelled from BRSDP and created his own party - the Social Democratic Federation which he left in 1927. In the same year Kazasov and a group of intellectuals created the Zveno Political Organisation. He published Zveno's "Zveno" magazine and "Izgrev (Sunrise)" newspaper. In early 1934 he separated from Kimon Georgiev and his group left Zveno and joined Aleksandar Tsankov's National Social Movement.