Which Promises Actually Matter? Election Pledge Centrality and Promissory Representation

Parties make hundreds of campaign promises but not all are seen by voters as central to a party's offering. Studies of government promise fulfilment accept that not all promises are equivalent but in practice treat all promises equally because they lack an appropriate means of measuring promise centrality. To demonstrate the importance of accounting for pledge fulfilment, we develop a conjoint experiment method to measure public opinion about promise centrality which can be used to construct centrality weights. We demonstrate this approach’s utility by examining the 2017 UK Conservative manifesto. Centrality weighting reduces our assessment of Conservative promise-keeping by 21 percentage points (1.3 standard deviations of typical promise completion rates found in comparative studies). Weighting increases the centrality of EU promises sevenfold, immigration promises sixfold, and reduces the centrality of miscellaneous administrative promises by more than half. These results illustrate that pledge centrality cannot be ignored when assessing pledge fulfillment.