How far can the media protect or undermine democratic institutions in unconsolidated democracies, and how persuasive can they be in ensuring public support for dictator's policies? We study this question in the context of Germany between 1929 and 1939. Using geographical and temporal variation in radio availability, we show that radio had a significant negative effect on the Nazi electoral support between 1929 and 1932, when political news were slanted against Nazi party. This effect was reversed in just 5 weeks following Hitler's appointment as chancellor and the transfer of control of the radio to the Nazis. Pro-Nazi radio propaganda caused higher vote for the Nazis in March 1933 election. After full consolidation of power, radio propaganda helped the Nazis to enroll new party members and encouraged denunciations of Jews and other open expressions of anti-Semitism. The effect of Nazi propaganda was not uniform. Depending on listeners' priors about the message, propaganda could be very effective or could backfire. Nazi radio was most effective in places where anti-Semitism was historically high and had a negative effect on the support for anti-Semitic policies in places with historically low anti-Semitism.