Leading figure in the study of American political institutions and the performance of American democracy. Much of her work has focused on the US presidency, including her book Who Leads Whom: Presidents, Policy, and the Public (2006), which makes a number of prominent arguments about how presidential decisions reflect and influence public opinion. The book is not only theoretically rich, but amasses strong empirical support from quantitative as well as qualitative evidence. In a number of influential papers, she explores similar themes regarding representation and accountability with respect to legislators and elected judges. Currently, she is engaged is several projects that explore how campaign donors influence policymaking. In addition, she has published several recent papers on the impact of electoral and policy uncertainty on economic outcomes.