This must be from his early years.
"Originally an advocate of radical left, Dos Passos' politics shifted to the conservative right in the latter half of his career."
Link: http://www.factmonster.com/ipka/A0760856.html
This must be from his early years.
It seems Dos Passos had broken with the left before this was written, having been disillusioned with Soviet Communism during the Spanish Civil War:
"Although he espoused the bohemian way of life, he had many non-bohemian friends. He and his wife often cruised the Mediterranean with the Murphys and found other elite oases of peace to refresh themselves from time to time. In 1936, The Spanish Civil War began. During this War, he went to Spain to make a documentary of the Loyalist actions, using Ernest Hemingway as narrator of the film. Angered by the dominating role the Russian communists were playing in the Loyalists side, Dos Passos grew even more disillusioned with communism. He quit the film over disputes with the Russian communists. His long-time and close friendship with Hemingway ended bitterly in an argument, as they found themselves on opposite sides of this dispute. After returning to the US, Dos Passos broke with the political left. He wrote a novel, Adventures of a Young Man, denunciating communism and criticizing the political Leftists."
The book mentioned, Adventures, was published in 1939.