[179] The result was a tremendous growth of membership in the labor unions, especially in the mass-production sector.[180] When the Flint sit-down strike threatened the production of General Motors, Roosevelt broke with the precedent set by many former presidents and refused to intervene; the strike ultimately led to the unionization of both General Motors and its rivals in the American automobile industry.[181]
While the First New Deal of 1933 had broad support from most sectors, the Second New Deal challenged the business community. Conservative Democrats, led by Al Smith, fought back with the American Liberty League, savagely attacking Roosevelt and equating him with socialism.[182] But Smith overplayed his hand, and his boisterous rhetoric let Roosevelt isolate his opponents and identify them with the wealthy vested interests that opposed the New Deal, strengthening Roosevelt for the 1936 landslide.[182] By contrast, labor unions, energized by labor legislation, signed up millions of new members and became a major backer of Roosevelt's re-elections in 1936, 1940, and 1944.