At the Seventh Congress he was also elected a member in the Executive Committee of the Communist International, entering its presidium, where he remained until August 1941. Subsequently, Stefanov engaged in a campaign against alleged Trotskyists, mirroring Soviet measures that led to the Great Purge; a committed Stalinist, he accused both Elena Filipescu and Marcel Pauker of having sided with Leon Trotsky. Although himself under suspicion from Soviet overseers, he fled to Moscow in 1938, after PCR activities had been made virtually impossible by authorities of the National Renaissance Front. Removed from the party's leadership in 1940, he was denounced in 1951 by the Central Committee of the PCR, which accused him of having been "divorced from the working class", of having introduced the theory of "neo-serfdom" ("see Constantin Dobrogeanu-Gherea"), as well as of having advocated a "liquidationist" policy of a united front with bourgeois parties in 1927. The actual leadership of the PCR inside Romania was taken over by Bela Breiner from 1938 until his death in 1940 and then by Ştefan Foriş. Stefanov was a friend of Georgi Dimitrov, who is credited with having rescued him from an almost certain doom after 1938. He spent the last decades of his life living in exile in Sofia, Bulgaria. In subsequent periods, Stefanov's image and status remained the subject of allegations inside Communist Romania: in 1961, the high-ranking Communist activist Valter Roman, who had been himself disgraced and rehabilitated by Gheorghe Gheorghiu-Dej, spoke out against former Communist politicians who had been purged at various stages, Stefanov included; he was interrupted by Petre Borilă, who notably added a claim that Stefanov had admired Nazism and had seen in it a path to a socialist economy. On his 80th birthday in 1963, the Bulgarian Communist government awarded Stefanov the country's top honour, the Order of Georgi Dimitrov. The award was viewed as a deliberate attempt to irritate Romania's leadership, and a sign of cooling relations between the PCR and the Bulgarian Communist Party. During the later part of his life, Stefanov collaborated with several Bulgarian newspapers and magazines, and also participated in friendship committees seeking to strengthen Bulgaria's relation with Romania, the Soviet Union, and Yugoslavia. He died in a car accident in October 1969.