Swing vote

A swing vote is a vote that is seen as potentially going to any one of a number of candidates in an election, or, in a two-party system, may go to either of the two dominant political parties. It usually comes from voters who are 'undecided' or who may change their preferences between candidates or parties. Such votes are usually sought after in election campaigns, since they can play a big role in determining the outcome.

A swing voter or floating voter is a voter who may not be affiliated with a particular political party (Independent) or who will vote across party lines. In American politics, many centrists, liberal Republicans, conservative Democrats, and inconsistent voters are considered "swing voters" since their voting patterns cannot be predicted as easily as voters in “safe seat” voters.

While the swing voter is ostensibly the target of most political activity during elections, another factor is the success of each party in rallying its core support. In a two-party system, those who become disillusioned with their once-favoured party are more likely to vote for a third-party or abstain than cross over.

Smaller groups that use voting to decide matters, such as chambers of parliament and supreme courts, can also have swing voters. The smaller the group, the more power swing voters can have. For example, on the Supreme Court of the United States, a court of nine judges, one judge may be seen as single-handedly deciding a case when four others are committed to each side.