As habitual consumers of political talk know, one of the most ancient arguments of American politics involves the relative emphasis campaigns should pay to persuasion and mobilization–to “base voters” and “swing” or more technically, “persuadable undecided” voters. Late in most competitive campaigns, of course, the ratio of voters that can be harvested via superior “mobilization” as compared to those in which “persuasion” tends to rise as voters make up their minds or simply lose interest. It’s a challenge not only for campaigns, but for observers, who often struggle to get a handle on the proportions of voters in the two categories.

That’s why two pieces in TNR today are worth reading. The first, by Bill Galston, reminds us there are indeed still undecided voters out there, and they have a tendency (though not always and not always by big margins) to break against incumbents at the end of campaigns. The second, by Nate Cohn, gets into comparisons of current candidate margins with the remaining undecided vote, which helps enormously:

In this election, the number of undecided voters is so small that there are only few states where a clear break would be sufficient to flip the outcome. In Wisconsin and Nevada, Obama already exceeds 49 percent, suggesting that undecided voters could only influence the outcome if Obama supporters turn out at lower rates than the polls anticipate. One state where Romney still retains a narrow path to victory through undecided voters is Ohio, where Obama holds a very slight lead of just 2.1 points in the RealClearPolitics average, 47.9 to 45.8. But if Romney won 55 percent of undecided voters and one percentage point vote for a third party candidate, Obama would still win Ohio by a 1.6-point margin, 50.3 to 48.7. Romney would need nearly 70 percent of undecided voters to carry the state—an exceptional performance. Colorado and Virginia are the two states close enough for undecided voters to more realistically make a difference, but, even there, turnout is a more critical question.

But there’s another reason it makes sense for Obama to focus on turnout rather than persuasion in the final days, assuming he has to make that choice, notes Cohn:

According to national polls, Obama is performing four points better among registered voters than likely voters. That’s well above the more typical 1 or 2 point gap and the main culprit appears to be strong Republican enthusiasm combined with low enthusiasm among young, Latino, and Democratic-leaning independent voters. Since Obama’s coalition is unusually dependent on low-frequency voters, Obama has more to gain from a strong turnout operation than previous candidates. Although it’s unclear whether Obama’s vaunted ground operation can rejuvenate turnout among infrequent Obama ’08 voters, the difference between a modest and high turnout among young and minority Obama supporters could easily decide the election. And it’s not just that turnout is important, it’s that Obama’s larger advantage among registered voters makes it an open question whether Obama could actually lose if minority and youth turnout rates approach ’08 levels, even if undecided voters broke in Romney’s direction.

The very nature of Obama’s coalition makes it hard, and essential, to turn it out. But if he does, he’s in a clear position to win no matter how many voters Moderate Mitt bamboozles.

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Ed Kilgore is a political columnist for New York and managing editor at the Democratic Strategist website. He was a contributing writer at the Washington Monthly from January 2012 until November 2015, and was the principal contributor to the Political Animal blog.