Romein's Marxism made him a controversial figure and affected his career when in 1938 he was a candidate for a professorship at the Municipal University of Amsterdam, where professors were appointed by the municipal council. On the one hand, the liberals and right-wing factions disliked Romein for his continued support of the Soviet Union; on the other hand, the communist faction headed by Romein's old friend Wijnkoop were upset about his openly criticizing of Soviet show trials, two years earlier. This criticism, however, won him some sympathy within SDAP faction. A majority that included Wijnkoop's communists voted against Romein's appointment. A year later, when a different professorship was vacant, Romein was appointed professor of Dutch history, this time with support from Wijnkoop and despite a vehement campaign against his candidature.