WASHINGTON – New polling shows John McCain with a 48-42 lead in the suburbs. And that may not be enough to overcome Barack Obama's dominance in urban areas.

"The suburbs are a major battleground," said Evans Witt , CEO of Princeton Research Associates, explaining the findings of a survey conducted for the National Center for Suburban Studies at Hofstra University, not far from Levittown, Long Island's iconic postwar suburb.

Mr. McCain's edge in rural areas is far wider, 51-35. But Mr. Obama holds a 57-34 lead in the cities – a pattern seen from northern Virginia to North Texas to the fringes of Denver. Suburbs have seen explosive growth for years. Immigration is a key engine, and newcomers and their offspring tend to vote for Democrats.

"This election, maybe the Republicans can still hold on," said Robert Lang, director of the Metropolitan Institute at Virginia Tech and a leading expert on suburban politics. "There are still a lot of white couples with kids in the suburbs."

Dallas and its environs provide a case study. He noted that Sen. John Kerry came close to beating President Bush in Dallas County in 2004, though that wasn't nearly enough to overcome the Bush strength in outlying areas.

"He almost beat the former governor," Dr. Lang said, noting that when Mr. Bush returns to Dallas after handing over the keys to Air Force One, he'll find it far bluer than when he moved away. "There's no chance Obama will lose Dallas County in this election. That's just the reality."

Collin County, just to the north, hasn't made the transition, but it's headed that way, Dr. Lang said – like many suburban counties, including many in battleground states.

"Plano is maturing. It's got light rail to it. It's got multifamily housing," he said, adding that only the deeply held conservatism of many residents has stalled a demographically inevitable shift. "In another state, that Plano-type county, and Plano city itself, would be already trending toward the Democrats."

As for the McCain-Obama race, the Hofstra poll revealed vulnerabilities for each side.

Suburban men favor Mr. McCain 51-40. Suburban women are evenly split – a gender gap both camps are eager to exploit.

Marriage and parenthood is a strong indicator of GOP sympathies. Unmarried suburbanites are more likely to support Mr. Obama. Soccer moms and dads lean toward Mr. McCain.

Mr. McCain's suburban support hinges mostly on wealthier white voters; he wins that demographic 2-to-1. But today's suburbs grow more ethnically and economically diverse every week.

Also, undecided suburbanites – the battleground within the battleground – resemble the archetypal Obama voter in many ways.

They want universal health care and a timeline for withdrawal from Iraq by 2-to-1 margins.

With more jobs than ever located in suburbia, economic stress is a disproportionate factor.

Half of suburbanites know someone who lost a job in the past year. Energy prices have pinched budgets. Home prices have plunged. Nest eggs have eroded.

"This has changed this year's political landscape," said Christopher Niedt, academic director of Hofstra's suburban studies center. "Whether that means enduring new political alliances remains to be seen."