The first problem with the poll is simple: nationwide voting is irrelevant. If Obama wins New York, California, Massachusetts and Illinois by 80-20 and loses every other state, he could actually win a majority of votes but he'd get drubbed in the election. The Electoral College matters, the national majority winner is irrelevant.
Then I noticed this anomaly: Obama holding a 53-40 lead in the "Midwest." That seemed like rank bs. Every poll in Minnesota, Wisconsin, Michigan, Ohio and Indiana has been close in recent days, even after McCain's poor week last week. Unless the Midwest consisted solely of Northern Illinois and Milwaukee, the result was out of line.
Sure enough, the poll is riotously unreliable. Don't take my word for it, check out these facts:
(1) the sample, including persons who "leaned" toward one party or another, was 54% Dem, 38% Republican.
(2) the largest spread in party identification in a presidential election since 1988 has been FOUR points -- the 1996 election when Clinton had a high approval rating. Even in 2006, when the Democrats ripped the Republicans in the Congressional elections, party ID was 38% Dem, 35% Rep., 27% independent/other.
More analysis from Kristen Soltis, a Republican pollster who notes the trends:
During presidential years, over the last five presidential elections, the biggest party ID gap was four points, and the greatest swing was four points as well.
Arguments can certainly be made that in this environment, Democrats should be expected to have a huge partisan shift in their favor. But note that in 2006, when Democrats clearly found enormous success at the ballot box, that the advantage in party ID was only three points (38-35). Polls leading up to the election showed party ID gaps as big as eleven points (Newsweek's poll on Oct 5-6, 2006), rarely showing party ID gaps of less than +5 for the Democrats.
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[Reacting to a CBS poll in August:] . . . a twelve point spread [in party affiliation]? Whether this is a blip or what consistently turns up in the numbers, I have incredible difficulty believing that a margin of that magnitude is an accurate reflection of the electorate. A six-point lead is within the realm of possibility given a really great year for Democrats. But a twelve-point spread is simply outside the bounds of history, given that in twenty years of political change and history, the greatest margin has been four.