If Sen. John McCain pulls out a stunning upset next Tuesday, he'll have the country club, not Sam's Club, to thank for it. Conversely, if Sen. Barack Obama maintains his lead and coasts to victory, it will likely be because he was able to persuade wealthier voters to take a chance on his economic vision. That's because while wealthy states remain firmly in the blue column, wealthy voters run deep red.

In 2000, the poorest voters in Mississippi (50th in nation in per capita income), Ohio (middle of the pack) and Connecticut (first in per capita income) were equally likely to vote for George W. Bush. The richest residents of the same three states diverged sharply, with more than three-quarters of wealthy Mississippians voting Republican, 60 percent in Ohio and less than half in Connecticut. This pattern held in 2004.

It turns out the mythical lower-income "values voter," who puts "God, guns and gays" before economic concerns is just that. The Republican edge in poorer states has little to do with the cultural concerns of lower-income voters, and far more to do with the intensity of GOP support by the wealthy in these states.

In graphical terms, this is represented by a steep incline in the likelihood of voting GOP as you move up the income scale in the classic red states. Battleground states, such as Ohio, show a more moderate slope. The urbanized anchors of blue America approach a flat line.

Andrew Gelman, a statistician at Columbia University, and his colleagues have documented these trends in their book, "Red State, Blue State, Rich State, Poor State: Why Americans Vote the Way They Do." Their findings answer several questions about the twists and turns of the 2008 presidential election. And the path to victory for McCain or Obama becomes clearer to imagine.

For starters, how has the seemingly hapless and relatively underfunded McCain campaign kept pace, at least until recently, with a man their own ads famously call "the biggest celebrity in the world"? And why is Obama now seemingly pulling away?

Because, until recently, the patterns that Gelman identified had held. For example, in early September, Pew Research had McCain leading Obama 53 to 39 among those Americans making $75,000 or more. Their latest poll has Obama up, 52 percent to 41 percent in this category - a 12-point swing in a matter of weeks. Pew's horse-race poll has Obama gaining six points overall during this period.

Another of Gelman's observations on recent voting patterns found that those who regularly attend church, regardless of what state they live in, are more likely to vote Republican - although the pattern is that much stronger in red states than blue. According to Pew, Obama has also gained 7 points in the last month with weekly churchgoing white mainline Protestants and 9 points with Catholics who attend weekly Mass, another likely cause for his recent surge.

Returning to a familiar campaign narrative, many ask whether Obama hasn't changed the map, particularly in poorer states with relatively large minority populations? There is little evidence that this is the case. In the 10 lowest-income states, McCain leads by an average of 16 points, trailing only in New Mexico, a classic battleground state. Similarly, nine of the 10 richest states look firmly Democratic in 2008. If you discount traditionally red Wyoming, which has catapulted from 28th in per capita income in 2000 to sixth today, based on natural gas revenues, it is a clean sweep. Among these, Obama has swung Colorado and Virginia into his column from the 2004 GOP column. So, in the 10 richest and 10 poorest states, only three look to be moving away from the party they favored in previous elections. Of these, two are simply falling into line with their fellow wealthier states, and one is continuing a pattern of vacillation between parties (although looking solidly Democratic at this point). Hardly a seismic shift between red and blue.

So, then, what should we look for in trying to figure out whether Obama's momentum will lead to a Reaganesque landslide or another electoral nail-biter? RealClearPolitics.com lists 85 electoral votes not solidly in the GOP or Democratic column - Florida, Georgia, Indiana, Missouri, Montana, North Carolina and North Dakota. If Obama can smooth the curve in the poor toss-up states (Georgia and North Carolina), and steepen it in richer ones (as he has done in Colorado and Virginia), he may well get a landslide. On the other hand, if McCain can maintain President Bush's popularity with wealthy churchgoers, particularly in the low- to moderate-wealth states still up for grabs, we could be in for a long night.