Joseph M. Bessette and J. Andrew Sinclair at RealClearPolicy look at detailed public opinion data about the death penalty.

To provide a rough summary of our findings: We can divide the electorate into three groups of different sizes. About a fifth of American voters oppose the death penalty in nearly every circumstance: These appear to be the truly committed opponents. About three fifths reliably support the death penalty: they favor it in theory and also want to have a death penalty law in their state. A final fifth of the American electorate approves of the death penalty in some way, in theory, but does not necessarily want the death penalty in their state.

Framed this way, there is more support for the death penalty than the 55% (Gallup) or 60% (Pew) numbers might suggest. This is not to say those numbers are “wrong” (with similar questions, we find similar results), but just that they understate death penalty support for the kinds of aggravated murders that make an offender eligible for capital punishment in American states. If a substantial proportion of death penalty “opponents” — as measured by Gallup and Pew — actually approve, at least theoretically, of the death penalty in some cases, their opposition is much softer than might be assumed. As prior research on this subject has demonstrated, changing crime rates or different media coverage might drive up support again, and these types of voters could potentially be satisfied with laws that focused on a few highly aggravated murders, provided special safeguards against mistaken convictions, or had other features to mitigate their concerns about implementation. Truly committed opponents are a small minority of voters