By Douglas Harbrecht, New Media Director July 10, 2008 Ah, the fickleness of the Campaign '08 polls. Remember Barack Obama's commanding 13% lead headed into the New Hampshire primary? (Nope, he lost to Hillary Clinton) Remember those Texas polls that showed him surging? (He lost to Clinton there, too.) Many polls have been out-of-kilter this year, and they will be right up to Nov. 4. But here's my theory: If Barack Obama leads by 6% or more over Labor Day weekend, he will likely win the presidency in a squeaker. If his lead is 5% or less, John McCain could well pull it out.Voter sentiment waxes and wanes continuously. But for decades, the Labor Day poll before every presidential election has provided a surprisingly accurate snapshot of the final outcome. In 2004, the CNN/USA Today/Gallup Labor Day poll showed incumbent George Bush leading by 2 percentage points over Democrat John Kerry among registered voters. Bush won by 3 points in November, 51%-48%. Going back to 1988, Bush's father held an 8 point lead in the Labor Day polls, and won by 7.8% over Democrat Michael Dukakis. It's been a reliable barometer. So what's different this year? Well, I'd argue it will likely be reliable again. But there very well could be a Bradley Effect in this historic national election, where a statistically significant number of white voters tell pollsters they are undecided or leaning toward voting for a candidate of color but then break strongly the other way in the voting booth. This phenomenon likely hurt Obama in the New Hampshire primary. And given the coolness of working-class white Democrats to his candidacy in the Ohio and Pennsylvania primaries, he may struggle mightily to win these important swing states this year. Many of those same folks may well tell pollsters they support Obama or are undecided, but then break strongly toward McCain on Election Day. I hope I'm wrong, that a decisive number of white people in America would tell pollsters they are undecided or leaning toward a candidate, knowing in their hearts they won't vote for that candidate because of his skin color. Obama leads by 6%-10% in most polls now. And all the dynamics of this race so far favor Obama and the Democrats -- a hunger for change among voters, a frightening slowdown in the economy and a chance for America to make history. But the nominating conventions are still to come, McCain has begun a TV marketing campaign to re-introduce himself to voters, and so much could change over the next few months. This has been a fascinating, groundbreaking election on many levels--and it's far from over yet.