It was so unseasonably warm in downtown Des Moines, Iowa, that Barack Obama could deliver his stump speech in his shirt sleeves on Friday. In fact, it was so sunny in late October, that it was hard to recall just how bitterly cold it was a year ago, when Obama was still struggling to get people to believe he could pull off a surprise victory in the state’s caucus contests.

The Obama campaign savors the symbolism of returning to its roots. It launched itself in Springfield, Illinois, in February 2007 and returned there 17 months later for the rollout of the new veep pick Joe Biden. It started its nomination fight in Des Moines and returned there on the night it won a majority of Democratic delegates.

So what is the deeper meaning of Des Moines now?

According to the McCain campaign, its internal Iowa polls have tightened to the point of a statistical tie. Public polls show nothing similar. Over the course of the last month, Obama’s lead has ranged from a low of 8 points to a high of 15 points.

Iowa is indeed a battleground state, with its seven electoral college votes. But its battleground status comes less from the polls than its column-switching patterns in the last two cycles. Al Gore won Iowa in 2000, while George W. Bush won it in 2004.

Obama staffers shrug their shoulders and smile when asked about their opponent’s polling in Iowa. They insist their own internal polling shows no slippage in Iowa, and nothing like a close contest.

So why visit Iowa now? First, Iowa is close to Illinois, and the candidate is returning home this afternoon to go trick-or-treating with his daughters before campaigning in Indiana and ending the day in Nevada. Second, the campaign canceled an earlier trip to Iowa so the candidate could fly to Hawaii to see his grandmother, who is gravely ill. And third, until Friday, Iowa has only seen Obama twice since he clinched the nomination.

As for Obama himself, it’s clearly irresistible to close the symbolic circle in Des Moines. “A whole new way of doing democracy started right here in Iowa, and it’s all across the country now,” he told a crowd of 25,000 supporters. “That’s how we’ve come so far, how we’ve come so close, because of you.”