What are swing voters?

Swing voters are voters who could realistically support candidates from either major political party in a given election, depending on the issues, candidates, and political climate of the moment. Swing voters are sometimes called persuadable voters, undecided voters, or independents, though these terms are not exactly synonymous. The behavior of swing voters often determines the outcome of close elections.

Both major parties typically have their core supporters who almost always vote for the same party regardless of circumstances. Swing voters are the relatively smaller group that decides between the parties based on candidates and issues, and shifts in this group can change election outcomes substantially.

Several different groups of voters can be considered swing voters at different times. Independents who do not identify strongly with either major party are often considered swing voters, though some self-identified independents actually lean reliably toward one party. Voters in particular demographic groups whose loyalty has shifted between parties (such as suburban women, working-class voters in industrial areas, or Hispanic voters) can be swing voters. Voters who support one party for most offices but cross over for particular candidates or in particular elections (sometimes called ticket-splitters) are also a kind of swing voter.

The number of true swing voters has declined significantly in recent decades as American politics has become more polarized along party lines. Voters increasingly identify with one party and stick with it across elections. Even self-identified independents often lean reliably toward one party. Studies suggest that the number of voters who genuinely shift between parties from election to election is relatively small, perhaps 5 to 15 percent of the electorate in most years.

Despite this, swing voters remain decisive in close elections, particularly in swing states (battleground states where both parties have realistic chances of winning). In a state where the result might be decided by a few thousand votes out of millions cast, swing voters who shift between elections can determine the outcome.

Campaigns spend significant resources targeting swing voters with persuasion messaging, while devoting substantial resources to mobilizing their base supporters who are already committed. Modern campaigns use sophisticated voter targeting based on data analytics to identify likely swing voters and tailor messaging to their concerns. Specific issues that have moved swing voters in recent elections include the economy, healthcare costs, immigration, abortion rights, and crime, among others. The combination of swing voter persuasion and base mobilization shapes most modern presidential and competitive Senate or gubernatorial campaigns.