As numerous studies have shown, the overwhelming majority of Americans who say there are “independent” lean toward one party or the other. Call them IINOs, or Independents In Name Only. IINOs who say they lean toward the Republicans think and vote just like regular Republicans. IINOs who say they lean toward the Democrats think and vote just like regular Democrats.
… [T]he “independent” group does include one sub-group whose members look and act more like swing voters. This is the so-called pure independents subgroup, those who say they do not lean toward either party. In 2008, they split their vote much more evenly between the parties—51-41 for Obama—and they have policy views that are not closely aligned with either party. But this is a small group, and because it tends to show low information, low involvement, and relatively low turnout, it is even smaller in the context of an actual election. In 2008, according to the NES, they were just 7 percent of all voters and only 20 percent of nominally independent voters.
(Chart by John Sides)