An election promise or campaign promise is a promise or guarantee made to the public by a candidate or political party that are trying to win an election.
Across the Western world, political parties are highly likely to fulfill their election promises. In the United States, platform positions offer important clues as to the policies that U.S. parties will enact. Over the past 30 years, Democratic and Republican congresspeople voted in line with their respective party platforms 74% and 89% of the time, respectively.
A 2017 study in the American Journal of Political Science found that for 12 countries (Austria, Bulgaria, Canada, Germany, Ireland, Italy, the Netherlands, Portugal, Spain, Sweden, the United Kingdom, and the United States) found that political parties fulfill their promises to voters to a considerable extent:
Parties that hold executive office after elections generally fulfill substantial percentages, sometimes very high percentages, of their election pledges, whereas parties that do not hold executive office generally find that lower percentages of their pledges are fulfilled. The fulfillment of pledges by governing executive parties varies across governments in ways that reflect power-sharing arrangements. The main power-sharing arrangement that impacts pledge fulfillment distinguishes between single-party governments and coalitions, not between governments with and without legislative majorities. We found the highest percentages of pledge fulfillment for governing parties in the United Kingdom, Sweden, Portugal, Spain, and Canada, most of which governed in single-party executives. We found lower percentages for governing parties in Germany, the Netherlands, Austria, Bulgaria, Ireland, and Italy, most of which governed in coalitions. Pledge fulfillment by U.S. presidential parties lies at the higher end of coalition governments, which suggests that U.S. presidents are more constrained than governing parties in single-party parliamentary systems, but less constrained than most governing parties in multiparty coalitions.
Other research on the United States suggests that Democratic and Republican congresspeople voted in line with their respective party platforms 74% and 89% of the time, respectively.