@jbooth - possibly, it sometimes depends on the smaller party. In Irish politics, typically coalitions are formed with one large party and another smaller one. In some cases (a rightwing party known as the progressive democrats) they have been very effective, while in others (the Greens) they have been completely pointless.

Normally, the smaller parties take the blame for the decisions of the larger one, which is a facet of irish politics which I have never been able to understand.