This book aims to shed light on two crucial questions about political parties: Why are America's parties different from those in Europe? And why did the party-centered American politics of the nineteenth century become a candidate-centered system during the twentieth century? The two questions are linked, in that to answer the first adequately requires the availability of an answer to the second. As with many issues in political science, the problem is not the absence of possible answers but that there are too many competing, and sometimes incompatible, explanations. Superficially plausible though some of these explanations are, one of the points that will become evident during the course of the book is that much that has been asserted over the years about America's parties has been taken out of context, is misleading, or is simply untrue.

In attempting to answer the two questions, this study examines how and why direct primary elections were introduced in the United States. The direct primary has been one of the most unusual features of American parties. In each state today the selection of candidates for public office takes the form of an election that is organized by a government agency, rather than the parties themselves, and is subject to state law. Candidates for most elected offices, with the notable exception of the presidency itself, are now chosen in such elections.