Despite these strengths, the Nazi Party might never have come to power had it not been for the Great Depression and its effects on Germany. By 1930 the German economy was beset with mass unemployment and widespread business failures. The SPD and the KPD parties were bitterly divided and unable to formulate an effective solution; this gave the Nazis their opportunity, and Hitler's message, blaming the crisis on the Jewish financiers and the Bolsheviks resonated with wide sections of the electorate. At the September 1930 Reichstag elections the Nazis won 18.3% of the vote and became the second-largest party in the Reichstag after the SPD. Hitler proved to be a highly effective campaigner, pioneering the use of radio and aircraft for this purpose. His dismissal of Strasser and appointment of Goebbels as the party's propaganda chief was a major factor. While Strasser had used his position to promote his own version of national socialism, Goebbels was totally loyal to Hitler and worked only to burnish Hitler's image.
The 1930 elections changed the German political landscape by weakening the traditional nationalist parties, the DNVP and the DVP, leaving the Nazis as the chief alternative to the discredited SPD and the Zentrum, whose leader, Heinrich Brüning, headed a weak minority government. The inability of the democratic parties to form a united front, the self-imposed isolation of the KPD and the continued decline of the economy all played into Hitler's hands. He now came to be seen as de facto leader of the opposition, and donations poured into the Nazi Party's coffers. Some major business figures such as Fritz Thyssen were Nazi supporters and gave generously but many other businessmen were suspicious of the extreme nationalist tendencies of the Nazis and preferred to support the traditional conservative parties instead.
During 1931 and into 1932, Germany's political crisis deepened. In March 1932 Hitler ran for President against the incumbent President Paul von Hindenburg, polling 30.1% in the first round and 36.8% in the second against Hindenburg's 49 and 53%. By now the SA had 400,000 members and its running street battles with the SPD and KPD paramilitaries (who also fought each other) reduced some German cities to combat zones. Paradoxically, although the Nazis were among the main instigators of this disorder, part of Hitler's appeal to a frightened and demoralised middle class was his promise to restore law and order. Overt anti-Semitism was played down in official Nazi rhetoric, but was never far from the surface. Germans voted for Hitler primarily because of his promises to revive the economy (by unspecified means), to restore German greatness and overturn the Treaty of Versailles, and to save Germany from communism.