 Her name was among those included on the letter denouncing the Dewey Commission's investigation of the Moscow Trials, and she also endorsed the CP-initiated call for the Third American Writers' Congress in 1939.While remaining pro-Soviet Union for the rest of her life, like many other leftist intellectuals of the time, Slesinger grew disillusioned with the Soviet Union in the wake of the Hitler-Stalin Pact of 1939.Maxim Lieber served as her literary agent, 1933–1937 and in 1941.