Because the results will change dramatically...
For instance,
Six months ago, in November of 2007, Hillary led by 15 points over Obama in NH. She won by 2.6.
That's a difference of 12.6.
Similarly,
NV - Clinton +25 (November 2007), Clinton 5.5 (Election Day),
Obama +19.5 (Difference)CA - Clinton +25 (November 2007), Clinton 9.6 (Election Day),
Obama +15.4 (Difference)SC - Clinton +2 (November 2007), Obama 28.9 (Election Day),
Obama +30.9 (Difference)PA - Clinton +20 (November 2007), Clinton 9.2 (Election Day),
Obama +10.8 (Difference)WI - Clinton +13 (November 2007), Obama 17.4 (Election Day),
Obama +30.4 (Difference)OH - Clinton +25 (November 2007), Clinton 10.1 (Election Day),
Obama +14.9 (Difference)Currently, six months before the election, Obama is trailing McCain by
one point in Ohio, Florida, and Michigan.
http://www.electoral-vote.com/evp2008/Obama/Maps/May19.htmlI realize the dynamics are different, but being down one point is not a bad place to be considering the states that are in play.