Margin of error: Two candidates, two journeys, one race of lost dreams

Washington (CNN) - When the race is done, the balloons have wilted, and the confetti has been swept up, Campaign 2012 may be marked more by its failures than its triumphs.

But here's the starkest failure in these final days before the vote: Neither candidate has made a convincing enough argument for his presidency to break free of the margin of error in the polls.