Government survival has been in the focus of interest for several decades. In parliamentary regimes, coalitional governments collapse more often than single-party governments as coalition partners can break the coalition (Warwick 1994). In this paper, I examine the conditions under which this is true. I argue that when in a coalition government the junior coalition partner is pivotal --that is the opposition is more unified-- the coalition is more stable than when the opposition is fragmented. Moreover, I show that in this case, junior coalition partners more often leave the coalitions than senior coalition partners. I argue that this is because pivotal junior coalition partners have bigger bargaining leverages and can get more financial compensation from their senior coalition partners than non-pivotal ones. In turn, when a party has more money it can sustain its core voters even if the government loses its popularity. Thus, pivotal junior parties are less pressured by the public opinion than non-pivotal ones. I provide empirical evidence for this theory by examining the structure of the legislative party systems, government spending patterns and coalition break-downs in 17 Western European Countries from 1970-2013.