As you settle in with your bowl of popcorn and drink to watch the quadrennial competition for America's highest office, you need a scorecard. You are eagerly anticipating seeing the national map light up in red and blue--a welcome reminder of our federalist design--but what should you be watching for? How will you know whether John McCain is doing well enough to have any shot of pulling off the upset?

There are only ten states that were decided by 5 percent or less in each of the last two presidential elections: Ohio, Nevada, Wisconsin, New Hampshire, Minnesota, Oregon (yes, Oregon), Pennsylvania, Iowa, New Mexico, and Florida (which was decided by 5.01 percent in 2004 if you're nitpicking). Not surprisingly, these states will be important in 2008.

But it's not quite as simple as that. Mostly because of widespread dissatisfaction with President Bush, the political landscape has become more fertile for the Democratic party over the last four years. In addition, the Democrats, who have had a habit of nominating candidates with rather modest personal appeal (e.g., Walter Mondale, Michael Dukakis, John Kerry) are putting forward a candidate who draws 200,000 people to hear him speak. Sure it was in Berlin, but still .  .  . Whatever his genuine merits as a statesman, Barack Obama is clearly a more formidable candidate than John Kerry--and probably than Al Gore.

In light of these changed factors in 2008, it seems rather unlikely that Obama will fail to win any states that either Gore or Kerry succeeded in

McCain needs to take Florida, Missouri, Colorado, Nevada, Virginia, West Virginia, North Carolina, and, most dauntingly, Ohio. He needs to go 8-0 in these states--in addition to winning all of the other states that Bush swept (which he should). If one of those eight lights up for Obama on election night, it's lights out for McCain.

It'll be lights out, that is, unless McCain can somehow win a state that Bush didn't sweep in 2000 and 2004. This is a tall order. The most likely possibility would seem to be New Mexico, New Hampshire, or Wisconsin. Over the last two elections combined, Wisconsin was the closest state, with an average margin of victory of 0.3 percent, but it went to the Democrat each time. New Mexico, which borders McCain's home state of Arizona, was the second closest, with an average margin of 0.4 percent, and Bush won it in 2004. New Hampshire, where McCain has twice done very well in GOP primaries, was decided by just 1.3 percent in each of the last two elections, with Bush winning in 2000 and Kerry in 2004. But if Obama does better nationally than Kerry or Gore did, which at this point looks like a near-certainty (especially as regards Kerry), then these states that were so tightly decided in the past two elections will likely swing his way. And polls currently suggest that Obama is doing even better in these three states than he is doing nationwide.