Obama, Romney and the 2012 battle for undecided voters

Conventional wisdom holds that with such a small number of voters still undecided, this presidential contest is a base election like 2004, with both candidates focused on turning out their respective party's hard-core supporters. Like much conventional wisdom, there's some truth in this. But it's far from the complete story.

First, there are nearly as many undecided voters today as in other recent elections. Gallup's managing editor told Politico on Aug. 9 that his organization's polling finds 6%-8% of voters are undecided. At this point in 2008, 10% were undecided in Gallup's tracking poll. In 2004, the figure in the CNN/USA Today/Gallup tracking was 8% and in 2000, 9%.

Second, some voters are weakly committed to their choice and could flip. For example, in the July 8 Washington Post/ABC News poll, 24% said they were undecided or could change their minds. In a close race, these voters are the principal source of potential movement. So both sides are working hard to identify and either reinforce or persuade them.

Swing voters are not the only source of movement in the electorate. Less than 60% of eligible voters generally bother to register and turn out. In 2008, 57.48% of the voting-age population turned out, the highest since 1968, when turnout hit 60.84%

To continue reading Mr. Rove's column in the Wall Street Journal, click here.