Multivariate analysis indicates that economic elites and organized groups representing business interests have substantial independent impacts on U.S. government policy, while average citizens and mass-based interest groups have little or no independent influence. The results provide substantial support for theories of Economic-Elite Domination and for theories of Biased Pluralism, but not for theories of Majoritarian Electoral Democracy or Majoritarian Pluralism.
The probability of policy change is nearly the same (around 0.3) whether a tiny minority or a large majority of average citizens favor a proposed policy change. ... A proposed policy change with low support among economically-elite Americans (one out of five in favor) is adopted only about 18 percent of the time, while a proposed change with high support (four out of five in favor) is adopted about 45 percent of the time.
Martin Gilens and Benjamin I. Page, "Testing Theories of American Politics: Elites, Interest Groups, and Average Citizens," Perspectives on Politics, vol. 12, no. 3 (September 2014), p. 572
When citizens are relatively equal, politics has tended to be fairly democratic. When a few individuals hold enormous amounts of wealth, democracy suffers. The reason for this pattern is simple. Through campaign contributions, lobbying, influence over public discourse, and other means, wealth can be translated into political power. When wealth is highly concentrated—that is, when a few individuals have enormous amounts of money—political power tends to be highly concentrated, too. The wealthy few tend to rule. Average citizens lose political power. Democracy declines.
Benjamin I. Page and Martin Gilens, Democracy in America?: What Has Gone Wrong and What We Can Do About It (University of Chicago Press: 2017), p. 19
Average Americans have little or no influence over the making of U.S. government policy. ... Wealthy Americans wield a lot of influence. By investing money in politics, they can turn economic power into political power.
Benjamin I. Page and Martin Gilens, Democracy in America?: What Has Gone Wrong and What We Can Do About It (University of Chicago Press: 2017), p. 90