A mandate is a social construct based on what is understood to be the will of the voters. Mandate theory proposes that political parties are vehicles for policy options. Voters choose from these options during elections, which then empowers the policies that have the most popular support and allows for their implementation. When voters overwhelmingly support a specific party or candidate in an election, it may be interpreted as a communication from the voters that they wish for the associated political platform to be implemented, creating a mandate for that platform. Mandates are based on the idea that all voters are equal, and popular assent from the group as a whole is necessary to govern. Those involved in politics look to mandates to determine what is expected by the voters and what they will consider acceptable. A mandate is desirable for political parties, as it gives them leeway in policy implementation. A party or candidate may claim to have a mandate, but it only confers a political advantage if this claim is widely accepted. Non-electoral governments, such as dictatorships and monarchies, may also claim to have a popular mandate to rule.
Mandates develop from the interpretation of elections. If it becomes widely accepted that the voters support a given platform, then it will be understood that a mandate exists, regardless of the actual wishes of the voters. There is no agreed upon metric for how much support a position must have—or be believed to have—before there is a mandate for its implementation. When a political mandate is unclear, it may be seen as the policy preferences of the median voter on a left–right political spectrum. This presents its own challenges when applied, as policy preferences are often more complex and have multiple dimensions.
Modern democracies do not consistently provide a majority mandate, as several competing parties offer different policies, requiring coalition governments to make compromises between their members. In the United States, the two-party system always results in one party having a majority in government that can be interpreted as a mandate. In the event of a coalition government, there is no single party with a popular mandate, as every party was supported by less than half of voters. Some political systems, such as that of the United Kingdom, frequently give a majority of legislative seats to a party that received only a plurality of the vote. In this case, the majority only carries a mandate if it is representative of the median voter. Policy does not necessary correspond to the platform of the dominant party, as it may still have to negotiate with other parties or otherwise have limits on its power to implement certain policies. Proportional representation allows for more nuanced voter preferences, but it also allows for a party with only plurality support to receive a majority of seats. In any coalition-based system, voters are unable to know what coalitions may form after an election, further distancing voter preferences from electoral results.
The existence of political mandate as a concept is challenged by supporters of deliberative democracy, who believe that parties are elected as representatives to negotiate and compromise between different policy proposals. Direct democracy bypasses the issue of mandates entirely as it allows voters to choose policies directly.