Single-issue politics involves political campaigning or political support based on one essential policy area or idea. Single-issue politics are a form of litmus test; common examples are abortion, taxation, environment, and gun politics.

One weakness of such an approach is that effective political parties are usually coalitions of factions or interest groups. Bringing together political forces based on a single intellectual or cultural common denominator can be unrealistic; though there may be considerable public opinion on one side of an argument, it does not necessarily follow that mobilizing under that one banner will bring results.

Single-issue politics may express itself through the formation of a single-issue party, an approach that tends to be more successful in parliamentary systems based on proportional representation than in rigid two-party systems (like that of the United States). Alternatively, it may proceed through political lobbying (see also pressure groups) or other forms of political expression external to normal representative government.

Very visible as it was in Western democracies in the second half of the twentieth century, single-issue politics is hardly a new phenomenon. In the 1880s, the third government of William Gladstone made British politics in practical terms single-issue, around the Home Rule Bill, leading to a split of the Liberal Party.