When and how do regional parties influence foreign policy in federal democracies with multiparty coalition governments? The existing literature has focused on situations of foreign policy disagreements between subnational parties and the central government in multinational states. By contrast, we argue that under varying conditions, central governments either decide to accommodate the preferences of small regional parties when designing foreign policies, or co-opt these regional parties to push their own foreign policy agenda. Some scholars looked at the role of decentralization and federal power arrangements in providing more control to political sub-units over the external affairs of a state. Other studies showed that certain coalition-building configurations facilitated the inclusion of the concerns of small parties in the foreign policy debate. Bridging these two literatures, we argue that both structural and agential conditions behind regional and national coalition building processes—visible in federal settings—affect foreign policy-making in different ways, and not necessarily toward disagreement and obstruction. To illustrate these hypothesized mechanisms, we look at two case studies in the Indian context: the role of regional parties in the debate over the US–India nuclear deal of 2008 and the role of regional parties in shaping India’s Sri Lanka policy from 2009 to 2014.

地区党何时，如何影响多党联合政府在联邦民主制国家的外交政策？现有文献集中于外交政策分歧的情况在多民族国家的地方政府和中央政府之间。相比之下，我们认为，在不同的条件下，中央政府要么在设计外交政策时决定适应小区域政党的偏好，要么联手这些区域政党推进自己的外交政策议程。一些学者研究了权力下放和联邦权力安排在为政治子单位提供对国家外部事务的更多控制权方面的作用。其他研究表明，某些联盟建设构型有助于在外交政策辩论中纳入小党的关切。结合这两种文献，我们认为，在联邦背景下可见的地区和国家联盟建设进程背后的结构和代理条件，都以不同的方式影响着外交政策的制定，而不一定会引起分歧和阻碍。为了说明这些假设的机制，我们在印度的背景下研究了两个案例研究：区域党在关于2008年美印核协议的辩论中的作用以及区域党在2009年至2014年影响印度的斯里兰卡政策的作用。