New York: Joseph Biden's experience in foreign policy may boost Barack Obama, just as Sarah Palin's gender may aid John McCain, but the biggest benefit these vice presidential nominees bring to their tickets is an instinctual understanding of the people most likely to decide this election.

These are the same voters who have determined the winner of not only the last five presidential contests but, more recently, control of Congress, governors' mansions and state houses.

These voters are suburbanites. They include the ever-growing number of people who have been either priced out of cities or have left urban and rural areas in search of more bathrooms and bedrooms or better services. And they are a powerful and increasingly disenfranchised group.

Although suburbanites once voted strongly for Republicans, today their preferences are harder to pin down. The reason for the change is both demographic and ideological: more minorities are moving to suburbia and bringing their Democratic voting tendencies with them. And the increasingly conservative image of the Republican Party at the national level has alienated suburban voters, who tend to be pragmatic they are socially liberal, fiscally conservative and averse to extremism of any stripe.

A recent study by researchers from Virginia Tech and the University of Utah identified the most politically competitive suburban counties in a dozen "swing" states, including Colorado, Florida, Michigan, Minnesota, Missouri, Ohio, Oregon, Pennsylvania, Virginia and Wisconsin. All 12 of those counties were suburban and five of them have seen recent presidential, congressional and gubernatorial races decided by less than five points, while most of their neighbouring urban and rural counties saw margins well in the double digits.

Skin colour

Indeed, it is counties like Arapahoe in Colorado, Bucks and Montgomery in Pennsylvania and Orange in Florida all former Republican bastions that will decide who becomes the next president. And they are all places where Obama is likely to need a lot of help.

Why? Because suburbanites are suspicious of city politicians, and much about Barack Obama from his erudite speaking style to his fondness for arugula screams "city slicker." And then there is race. The nation's most-segregated communities are in the suburbs. While many suburbanites would never think of themselves as racist, it's fair to say that the colour of Obama's skin may make them uncomfortable.

Obama did well among suburban Democrats in several primaries, and the growing number of minorities in the suburbs will help him. But the white working class is still sitting on their white picket fences.

To be sure, McCain needs a lot of help too in getting suburbanites behind him. As the son of a naval officer and a career naval pilot himself, McCain spent many years on military bases far removed from the leafy lanes beyond the city lines. And as a Republican, he can no longer take the suburbs for granted. That's where Biden and Palin come to the rescue.

As a long-time resident and former local official in the Wilmington, Del., suburb of New Castle, Biden knows the suburbs. He went to school in the suburbs, raised his family there and started his political career there. He has wrestled with the fact that the suburbs are more congested and polluted and they're less fiscally able to improve schools when more and more children don't speak English. Their downtowns are crumbling, public transportation is abysmal, sewer systems are overburdened and affordable housing is non-existent.

Palin, a self-described "suburban hockey mom," also knows this territory well. Although Wasilla, Alaska, is a newer suburb that hasn't experienced quite the deterioration or demographic change of Biden's type in the East and Midwest, she knows from her mayoral days that suburban voters are obsessed with schools, property taxes and affordable housing.

If Barack Obama and John McCain want to win in November, they'll make the suburbs and their challenges a major priority.