Alan Wolfe is a contributing editor and director of the Boisi Center for Religion and American Public Life at Boston College.

Each presidential election, the pundits tell us, hangs on a crucial variable that divides one party from the other. Once it was income, as working-class people who were union members tended to vote Democratic while wealthier suburbanites voted Republican. Then it became church attendance: Irrespective of income, or even religion, if you went to houses of worship frequently, you were likely to be Republican, and if you stayed home on Sundays (or Fridays or Saturdays), you leaned Democratic.

This year's big dividing point, if a brand-new Washington Post/ABC News poll is to be believed, is education: Whites without a college degree favor McCain by 17 percent while those with one prefer Obama by 9 percent. If this trend continues, the implications for American politics deserve a bit of speculation.

For one thing, a divide such as this suggests that Democrats will continue to expand access to higher education while Republicans will oppose it. Here one must note the arguments of the conservative writer Charles Murray who, long before this particular poll was published, began arguing that they are too many college educated people in America. This makes little sense in economic terms in a knowledge-based world, but if you like Republicans in power, it makes a great deal of sense in political terms.

The Post/ABC poll did not provide data on what kind of college respondents attended, but it is likely that the more selective the college from which one graduates, the more likely one will be to vote Democratic. Anticipating such a result, the younger candidates of both parties in the present election perfectly reflect this development: Obama is a Harvard Law School graduate and Sarah Palin attended five not very distinguished colleges in six years. Expect, if the Republicans win, greater efforts by people such as Senator Charles Grassley (R-Iowa) to regulate the endowments of the most selective colleges and universities.

The education gap is likely to exacerbate the tendency of Democrats to speak in policy terms while Republicans appeal to guts, instinct, and emotion. If this trend continues, the Republican Party, which contains both elitist and populist elements, will move more decisively toward the latter and away from the former. If the Palin choice indicates any sense of direction, the Republicans may soon nominate a candidate who never attended college at all.

But this trend may not continue. When religion differentiated the parties, Democrats claimed to be people of faith themselves, downplaying their membership in mainline denominations and trying to appeal to evangelicals by speaking like them. Will the same thing happen as they try to make inroads among white working-class voters who never attended college by claiming that the Ivy League college they attended was actually chosen for them by their parentsm, or by using use their knowledge of Plato or Machiavelli to keep their knowledge of Plato and Machiavelli a secret? Or will Democrats resolve their own tension between elitism and populism by insisting that, to govern a world as complex as the one we inhabit, a little knowledge is not a dangerous thing?

Whatever happens, the effects, while important, will also be temporary. The thing about these variables that divide the electorate is that they always change. Next time around, the effects of education may even out and the electorate could be divided between those whose mortgages survived the great bailout crisis of 2008 and those that did not.

--Alan Wolfe