The Taft administration sought reductions to trade tariffs, then a major source of governmental income, but the Payne–Aldrich Tariff Act of 1909 was heavily influenced by special interests. Taft continued and expanded his predecessor's efforts to break up trusts, launching cases against U.S. Steel and other companies. The Republican Party had made the high tariff the central plank of their economic policy since the end of the Civil War, but Taft and some other Republicans had come to believe that the Dingley Act had set the rates too high. Though the high tariff protected domestic manufacturing, it also hurt U.S. exports and raised the cost of living for the average American. Many saw the tariff as a de facto regressive tax on consumers, and instead favored policies that would shift the tax burden to corporations and high earners.