Tracking the diminishing poll numbers has always been interesting- support for the war could only go down from the 88% support Americans gave it in October of 2001. But 2009 has been a more significant turning point than any previous year.
In December, 2008, 56% supported the war. That number dropped to 53% in April, 51% in May, 41% in September, and now rests at 39%, the lowest figure of the war.
The reason for this probably economic. We are all weathering a really harsh recession, and the notion of blowing billions of dollars on a hopeless war thousands of miles away is probably turning a lot of people against the war. Government spending on war is particularly sensitive now that health care reform opponents criticize the relatively modest price significant improvements would require. The dip could also be a response to the 48 U.S deaths in August and 45 in July, the two deadliest months of the entire war for U.S soldiers.
To dissect this poll a little further- 23% of Democrats currently support the war, along with 39% of independents and 62% of Republicans. That Republican figure has dropped 8% from a poll taken only two weeks ago, and accounts for the shift in overall numbers.