The Main Stream Media (MSM) is using polls to influence the election. They have attempted to build a groundswell of support for their candidate. They knew the real numbers favor President Bush, so the best they can do is continue with it is too close to call.
I don't think they have thought this all the way through. When the elections turns out to be a landslide for President Bush, all the predictions, and all the polls that showed "it was too close to call" will come under suspicion.
Pre-talk radio, and pre-internet, the dishonest efforts to influence voters would have been swept down the memory hole, they certainly would not revisit how they could have been so wrong.
But now, they have gone on record, and that record is available for anyone with access to a computer and the internet.
I think this is why Zogby is officially changing his position. He has done all he could to help Kerry,now is the time to save his own skin.