We develop a new theory of vote switching by legislators that defect from party line voting. In our model, ideological candidates select their party label and, once elected, vote in parliament. Political parties select their policy platform as to maximize votes while preserving their candidates’ loyalty. We find that legislators that defect from party line voting arise within the majority party. Besides, the more legislators care about their ideology and the less about their own reputation, the more they defect from party line voting. Interestingly, when a party has larger electoral advantage and its candidates sufficiently care about their reputation, such a party can propose a more polarized policy to avoid party defectors. Our model suggests that polarization incentivizes loyalty. Finally, we discuss the robustness of our results in multi-party systems and multi-constituency systems.

我们开发了一种新的立法者投票转换理论，该理论从党派投票中脱颖而出。在我们的模型中，思想考生选择在议会他们的党标签，一旦当选，投票。政党选择其政策平台是在保持候选人忠诚的同时最大化选票。我们发现，在多数党内产生了从党派投票中脱颖而出的立法者。此外，立法者越在乎自己的意识形态，越不在乎自己的声誉，他们越倾向于党派投票。有趣的是，当一个政党拥有更大的选举优势并且其候选人充分关心自己的声誉时，该政党可以提出一种更加两极化的政策来避免党内叛逃者。我们的模型表明，两极分化可以激发忠诚度。最后，