Political parties and democratic politics go hand in hand. Since parties matter, it matters too when elected politicians change party affiliation. This book shows why, when, and to what effect politicians switch parties in pursuit of their goals, as constrained by institutions and in response to their environments.

This book is the first systematic study of the causes and consequences of legislative party switching in the US. It provides a sophisticated analysis combining quantitative data from Congress and state legislatures with elite interviews with switchers, non-switchers, and a party leader, including a 'real time' look into the decision.

How much autonomy do elected politicians have to shape and reshape the party system on their own, without the direct involvement of voters in elections?

Party switching, or changing one’s political party affiliation, is a surprisingly widespread and persistent phenomenon among members of parliament (MPs) in old and new democracies alike. Switching gives voters the impression of a lack of legislator accountability and representation, and may indicate weak parties or government instability. Why do some MPs risk their careers, prestige, and chances of reelection for oftentimes uncertain payoffs? Extant research on party switching frames this behavior as an individual phenomenon, based on rational calculations to further goals of vote, office, or policy-seeking. Yet in the new democracies of Central and Eastern Europe, I find that party switching is largely a group phenomenon, which has heretofore received little attention. Building upon established research on political parties, party systems, and legislator behavior, I develop a theory of group-based defection that addresses this gap in the literature. I argue that MPs pursue political ambition in groups in which they share political goals—the pursuit of collective ambition is thus an alternative means to achieving their objectives. These groups are formed around, or defined by, social identities that are common or shared among individual MPs. By switching political parties as part of a group, individual MPs are able to more effectively pursue their political ambition.

This book challenges the approach of relying on election outcomes to analyse party systems, contending that changes can be also identified and documented beyond the scope of parliamentary elections through legislative party switching. It argues that significant party system changes occur often within parliamentary terms, and legislative party switching is not a pathological feature of democracy but rather an integral component of democratic party systems. Offering a comprehensive and specific theoretical framework for party switching and based on a novel and exhaustive database from Czech Republic, Lithuania, and Poland, the book examines the determinants for, and implications of, legislative party switching in Central and Eastern Europe. This book will be of key interest to scholars and students of legislative studies, party politics, Central and East European Politics and more broadly to comparative politics and government.

The Republican party has adopted a two-track strategy to attract Democratic defectors and turn them into partisan Republicans. First, the party has made direct appeals to rank-and-file Democrats during and after campaigns. Second, the party has targeted Democratic officeholders for conversion. By contrast, the Democratic party has been much less active in promoting party switches. In this book, a number of prominent political figures talk about realignment. Many have switched parties, and their thoughts reflect their reasons.