The immortal words of Brent Musberger seem apropos here:
President Bush leads Sen. John Kerry by 8 points among likely voters, the USA TODAY/CNN/Gallup Poll shows, a narrower advantage than Bush held in mid-September and one that puts him at the edge of the survey's margin of error.
At this rate, John Kerry will be ahead of President George W. Bush and can win the election -- so long as it's held at the end of January 2005. Of course, using the same logic, Bush's lead amongst registered voters will have risen to 19% by that time:
Among all registered voters, the president's lead widened a bit to a statistically significant 11 percentage points.
(I thought the post title above was better than "Shrinkage.")